diff --git a/src/component/modem.lua b/src/component/modem.lua
index ab088c4..90c8e51 100644
--- a/src/component/modem.lua
+++ b/src/component/modem.lua
@@ -5,6 +5,24 @@ compCheckArg(1,wireless,"boolean")
 local socket = require("socket")
 local ser = require("loot.OpenOS.lib.serialization")
 
+local function cerror(...)
+	local args = table.pack(...)
+
+	local sep = ''
+
+	for _,arg in pairs(args) do
+		local p;
+		if (type(arg) == "userdata") then p = "userdata"
+		elseif (type(arg) == "string") then p = arg
+		else p = ser.serialize(arg) end
+		io.stderr:write(sep .. tostring(_) .. '=' .. p)
+		sep = ','
+	end
+
+	io.stderr:write('\n')
+	io.stderr:flush()
+end
+
 -- yes, global
 modem_host = {}
 
@@ -24,14 +42,14 @@ modem_host.clients = {}
 -- [port_number] = true when open
 modem_host.open_ports = {}
 
-function modem_host.createPacketArray(t, address, port, ...)
-	compCheckArg(1,t,type(""))
-	compCheckArg(2,address,type(""),type(0))
-	compCheckArg(3,port,type(0))
+function modem_host.createPacketArray(packetType, address, port, ...)
+	compCheckArg(1,packetType,"string")
+	compCheckArg(2,address,"string","number")
+	compCheckArg(3,port,"number")
 
 	local packed =
 	{
-		t,
+		packetType,
 		address,
 		modem_host.id,
 		port,
@@ -43,7 +61,7 @@ function modem_host.createPacketArray(t, address, port, ...)
 end
 
 function modem_host.packetArrayToPacket(packed)
-	compCheckArg(1,packed,type({}))
+	compCheckArg(1,packed,"table")
 	assert(#packed >= 5)
 
 	local packet = {}
@@ -54,70 +72,75 @@ function modem_host.packetArrayToPacket(packed)
 	packet.distance = packed[5]
 	packet.payload = {}
 
-	for i=6,#packed do
-		table.insert(packet.payload, packed[i])
+	-- all other keys will be index values but may skip some (nils)
+	for k,v in pairs(packed) do
+		if k > 5 then
+			packet.payload[k-5] = v
+		end
 	end
 
 	return packet
 end
 
 function modem_host.packetArrayToDatagram(packed)
-	compCheckArg(1,packed,type({}))
+	compCheckArg(1,packed,"table")
 
 	local datagram = ser.serialize(packed)
 	return datagram .. '\n'
 end
 
 function modem_host.packetToPacketArray(packet)
-	return
+	local packed =
 	{
 		packet.type,
 		packet.target,
 		packet.source,
 		packet.port,
 		packet.distance,
-		table.unpack(packet.payload or {})
 	}
-end
 
-function modem_host.datagramToPacketArray(datagram)
-	compCheckArg(1,datagram,type(""))
-	local packed = ser.unserialize(datagram)
+	if packet.payload then
+		for i,v in pairs(packet.payload) do
+			packed[i+5] = v
+		end
+	end
+
 	return packed
 end
 
+function modem_host.datagramToPacketArray(datagram)
+	compCheckArg(1,datagram,"string")
+	return ser.unserialize(datagram)
+end
+
 function modem_host.datagramToPacket(datagram)
-	local packed = modem_host.datagramToPacketArray(datagram)
-	local packet = modem_host.packedToPacket(packed)
-	return packet
+	return modem_host.packedToPacket(modem_host.datagramToPacketArray(datagram))
 end
 
 function modem_host.packetToDatagram(packet)
-	local packed = modem_host.packetToPacketArray(packet)
-	local datagram = modem_host.packetArrayToDatagram(packed)
-	return datagram
+	return modem_host.packetArrayToDatagram(modem_host.packetToPacketArray(packet))
 end
 
 function modem_host.readDatagram(client) -- client:receive()
 	local raw, err = client:receive()
-	if raw then cprint("received: " .. raw) end
+	if raw then cerror("readDatagram", raw) end
 	return raw, err
 end
 
 function modem_host.readPacketArray(client) -- client:receive()
 	local datagram, err = modem_host.readDatagram(client)
-	if not datagram then return nil, err end
+	if datagram == nil then return nil, err end
 	return modem_host.datagramToPacketArray(datagram)
 end
 
 function modem_host.readPacket(client) -- client:receive()
 	local packed, err = modem_host.readPacketArray(client)
-	if not packed then return nil, err end
+	if packed == nil then return nil, err end
 	return modem_host.packetArrayToPacket(packed)
 end
 
 function modem_host.sendDatagram(client, datagram)
-	cprint("sending: " .. datagram)
+	cerror("sendDatagram", datagram)
 	return client:send(datagram)
 end
 
@@ -132,33 +155,37 @@ function modem_host.sendPacket(client, packet)
 end
 
 function modem_host.broadcast(packet)
-	-- only host broadcasts
-	-- this method will be hit for all broadcasted messages
-	-- but nonhosting clients will simply not repeat the broadcast
+	-- we assume packet.target == 0
 	if modem_host.hosting then
-		local datagram = modem_host.packetToDatagram(packet)
 		for addr,client in pairs(modem_host.clients) do
-			modem_host.sendDatagram(client, datagram)
+			packet.target = addr
+			modem_host.sendPacket(client, packet)
 		end
+		-- and self
+		packet.target = modem_host.id
+		modem_host.dispatchPacket(packet)
+	else
+		-- let host broadcast to all clients
+		modem_host.sendPacket(modem_host.socket, packet)
 	end
 end
 
 function modem_host.validTarget(target)
 	if target ==  0 then
-		return true
+		return true -- broadcast
 	end
 
 	if target == modem_host.id then
-		return true
+		return true -- dispatch will add to machine signals
 	end
 
 	if not modem_host.hosting then
-		return false
+		return true -- dispatch can handle sending to host
 	end
 
 	for address,client in pairs(modem_host.clients) do
 		if address == target then
-			return true
+			return true -- we are hosting and know about this target
 		end
 	end
 
@@ -178,9 +205,9 @@ end
 
 function modem_host.dispatchPacket(packet)
 	if packet.target == modem_host.id then
-			if obj.isOpen(packet.port) then
-				table.insert(machine.signals, modem_host.packetToPacketArray(packet))
-			end
+		if obj.isOpen(packet.port) then
+			table.insert(machine.signals, modem_host.packetToPacketArray(packet))
+		end
 	elseif modem_host.hosting then -- if hosting we will route
 		for source,client in pairs(modem_host.clients) do
 			if source == packet.target then
@@ -194,59 +221,55 @@ function modem_host.dispatchPacket(packet)
 end
 
 function modem_host.processPendingMessages()
-	-- computer address seems to be applied late
-	if not modem_host.id then
-		modem_host.id = component.list("computer",true)()
-		assert(modem_host.id)
+	-- do not try to process anything if this machine is not even connected to a message board
+	-- not wrong without this, this is a simple optimization
+	if not modem_host.connected then
+		return
 	end
 
-	modem_host.recvPendingMessages()
-
-	for _,packet in pairs(modem_host.messages) do
+	modem_host.acceptPendingClients()
 
+	for _,packet in modem_host.allPendingMessages() do
 		if packet.type == 'modem_message' then
 			-- broadcast if no target
 			if packet.target == 0 then
-				modem_host.broadcast(packet) -- ignored by clients
-
-				-- clean up for broadcasting to self
-				packet.target = modem_host.id
+				modem_host.broadcast(packet)
+			else
+				modem_host.dispatchPacket(packet)
 			end
-
-			modem_host.dispatchPacket(packet)
+		elseif packet.type == 'host_shutdown' then
+			modem_host.host_shutdown = true
 		end
 	end
-
-	modem_host.messages = {}
 end
 
-function modem_host.recvPendingMessages()
+function modem_host.acceptPendingClients()
 	if modem_host.hosting then
 		while true do
 			local client = modem_host.socket:accept()
-			if not client then
+			if client == nil then
 				break;
 			end
 
 			local handshake, err = modem_host.readPacket(client) -- client:receive()
-			if not handshake then
+			if handshake == nil then
 				client:close()
 			else
 
 				local connectionResponse
 				local accepted = false
 				if handshake.type ~= "handshake" then
-					connectionResponse = modem_host.createPacketArray("handshake", modem_host.id, -1, 
+					connectionResponse = modem_host.createPacketArray("handshake", 0, -1, 
 						false, "unsupported message type");
 				elseif modem_host.validTarget(handshake.source) then -- repeated client
-					connectionResponse = modem_host.createPacketArray("handshake", modem_host.id, -1, 
+					connectionResponse = modem_host.createPacketArray("handshake", 0, -1, 
 						false, "computer address conflict detected, ignoring connection");
 				else
 					client:settimeout(0, 't')
 					modem_host.clients[handshake.source] = client
 					accepted = true
 
-					connectionResponse = modem_host.createPacketArray("handshake", modem_host.id, -1, true);
+					connectionResponse = modem_host.createPacketArray("handshake", 0, -1, true);
 				end
 
 				modem_host.sendPacketArray(client, connectionResponse)
@@ -256,27 +279,45 @@ function modem_host.recvPendingMessages()
 				end
 			end
 		end
+	end
+end
 
-		-- recv all pending packets
-		for source, client in pairs(modem_host.clients) do
-			local packet, err = modem_host.readPacket(client)
-			if packet then
-				modem_host.pushMessage(packet)
-			elseif err ~= "timeout" then
-				client:close()
-				modem_host.clients[source] = nil
-			end
+function modem_host.allPendingMessages()
+	local msgIt = function(...)
+		if #modem_host.messages > 0 then
+			return 0, table.remove(modem_host.messages, 1)
 		end
-	elseif modem_host.socket then
-		while true do
-			local packet, err = modem_host.readPacket(modem_host.socket)
-			if packet then
-				modem_host.pushMessage(packet)
-			else
-				break
+
+		if modem_host.hosting then
+			for source, client in pairs(modem_host.clients) do
+				local packet, err = modem_host.readPacket(client)
+				if packet then
+					return 0, packet
+				elseif err ~= "timeout" then
+					client:close()
+					modem_host.clients[source] = nil
+				end
+			end
+		elseif modem_host.socket then
+			while true do
+				local packet, err = modem_host.readPacket(modem_host.socket)
+				if packet then
+					return 0, packet
+				else
+					if err ~= "timeout" then
+						if not modem_host.host_shutdown then
+							error("modem host was unexpectedly lost")
+						end
+						modem_host.connected = false
+						modem_host.connectMessageBoard()
+					end
+					break
+				end
 			end
 		end
 	end
+
+	return msgIt, nil, 0
 end
 
 function modem_host.createNewMessageBoard()
@@ -316,6 +357,21 @@ function modem_host.connectMessageBoard()
 		return true
 	end
 
+	if modem_host.host_shutdown then
+		modem_host.socket:close()
+	end
+
+	modem_host.socket = nil
+	modem_host.clients = {}
+	modem_host.messages = {}
+	modem_host.host_shutdown = nil
+
+	-- computer address seems to be applied late
+	if modem_host.id == nil then
+		modem_host.id = component.list("computer",true)()
+		assert(modem_host.id)
+	end
+
 	local ok, info, critical = modem_host.joinExistingMessageBoard()
 
 	if not ok and critical then
@@ -332,12 +388,37 @@ function modem_host.connectMessageBoard()
 
 	modem_host.socket:settimeout(0, 't') -- accept calls must be already pending
 	modem_host.connected = true
-	modem_host.clients = {}
-	modem_host.messages = {}
 
 	return true
 end
 
+function modem_host.halt(bReboot)
+	compCheckArg(1,bReboot,"boolean")
+	obj.close() -- close all virtual ports
+
+	-- if only rebooting, pending messages don't need to be pumped and no one needs to be notified
+	if modem_host.connected and not bReboot then
+
+		if modem_host.hosting then
+			for addr,csocket in pairs(modem_host.clients) do
+				local notification = modem_host.createPacketArray("host_shutdown", addr, -1);
+				modem_host.sendPacketArray(csocket, notification)
+			end
+
+			-- close all client connections
+			for _,c in pairs(modem_host.clients) do
+				c:close()
+			end
+
+			modem_host.hosting = false
+			modem_host.clients = {} -- forget client socket data
+		end
+
+		-- close real port
+		modem_host.socket:close()
+	end
+end
+
 local wakeMessage
 local strength
 if wireless then
@@ -352,67 +433,72 @@ local function checkPort(port)
 end
 
 function obj.send(address, port, ...) -- Sends the specified data to the specified target.
-	cprint("modem.send",address, port, ...)
 	compCheckArg(1,address,"string")
 	compCheckArg(2,port,"number")
 	port=checkPort(port)
 
+	-- we cannot send unless we are connected to the message board
+	if not modem_host.connectMessageBoard() then
+		return false
+	end
+
 	local packed = modem_host.createPacketArray("modem_message", address, port, ...)
 	local packet = modem_host.packetArrayToPacket(packed)
-	return modem_host.dispatchPacket(packet)
+	modem_host.pushMessage(packet)
+	return true
 end
 
 function obj.getWakeMessage() -- Get the current wake-up message.
-	cprint("modem.getWakeMessage")
 	return wakeMessage
 end
 
 function obj.setWakeMessage(message) -- Set the wake-up message.
-	cprint("modem.setWakeMessage",message)
 	compCheckArg(1,message,"string","nil")
 	wakeMessage = message
 end
 
 function obj.close(port) -- Closes the specified port (default: all ports). Returns true if ports were closed.
-	cprint("modem.close",port)
 	compCheckArg(1,port,"number","nil")
 	if port ~= nil then
 		port=checkPort(port)
 	end
 
-	if not obj.isOpen(port) then
-		return false;
+	-- nil port case
+	if port == nil then
+		if not next(modem_host.open_ports) then
+			return false, "no open ports"
+		else
+			modem_host.open_ports = {} -- close them all
+		end
+	elseif not obj.isOpen(port) then
+		return false, "port not open"
+	else
+		modem_host.open_ports[port] = nil
 	end
 
-	modem_host.open_ports[port] = nil
 	return true
 end
 
 function obj.maxPacketSize() -- Gets the maximum packet size (config setting).
-	cprint("modem.maxPacketSize")
 	return settings.maxNetworkPacketSize
 end
 
 if wireless then
 	function obj.getStrength() -- Get the signal strength (range) used when sending messages.
-		cprint("modem.getStrength")
 		return strength
 	end
 	function obj.setStrength(newstrength) -- Set the signal strength (range) used when sending messages.
-		cprint("modem.setStrength",newstrength)
 		compCheckArg(1,newstrength,"number")
 		strength = newstrength
 	end
 end
 
 function obj.isOpen(port) -- Whether the specified port is open.
-	cprint("modem.isOpen",port)
 	compCheckArg(1,port,"number")
 	return modem_host.open_ports[port] ~= nil
 end
 
 function obj.open(port) -- Opens the specified port. Returns true if the port was opened.
-	cprint("modem.open",port)
 	compCheckArg(1,port,"number")
 	port=checkPort(port)
 
@@ -432,12 +518,10 @@ function obj.open(port) -- Opens the specified port. Returns true if the port wa
 end
 
 function obj.isWireless() -- Whether this is a wireless network card.
-	cprint("modem.isWireless")
 	return wireless
 end
 
 function obj.broadcast(port, ...) -- Broadcasts the specified data on the specified port.
-	cprint("modem.broadcast",port, ...)
 	compCheckArg(1,port,"number")
 	port=checkPort(port)
 
@@ -448,7 +532,8 @@ function obj.broadcast(port, ...) -- Broadcasts the specified data on the specif
 
 	local packed = modem_host.createPacketArray("modem_message", 0, port, ...)
 	local packet = modem_host.packetArrayToPacket(packed)
-	return modem_host.dispatchPacket(packet)
+	modem_host.pushMessage(packet)
+	return true
 end
 
 local cec = {}
diff --git a/src/component/screen_sdl2.lua b/src/component/screen_sdl2.lua
index 64b3d99..bdec8dd 100644
--- a/src/component/screen_sdl2.lua
+++ b/src/component/screen_sdl2.lua
@@ -102,6 +102,8 @@ local window, renderer, texture, copytexture
 local function createWindow()
 	if not window then
 		window = SDL.createWindow("OCEmu - screen@" .. address, SDL.WINDOWPOS_CENTERED, SDL.WINDOWPOS_CENTERED, width*8, height*16, SDL.WINDOW_SHOWN)
+		SDL.setWindowGrab(window, SDL.FALSE)
+
 		if window == ffi.C.NULL then
 			error(ffi.string(SDL.getError()))
 		end
diff --git a/src/main.lua b/src/main.lua
index ca8beb6..6ef0bf8 100644
--- a/src/main.lua
+++ b/src/main.lua
@@ -294,8 +294,10 @@ function resume_thread(...)
 			machine.deadline = elsa.timer.getTime() + results[2]
 		elseif type(results[2]) == "boolean" then
 			if results[2] then
+				modem_host.halt(true)
 				boot_machine()
 			else
+				modem_host.halt(false)
 				elsa.quit()
 				error("Machine power off",0)
 			end