diff --git a/direct/src/plugin/Sources.pp b/direct/src/plugin/Sources.pp
index 678f79e092..9cbde330ad 100644
--- a/direct/src/plugin/Sources.pp
+++ b/direct/src/plugin/Sources.pp
@@ -14,6 +14,7 @@
     handleStream.cxx handleStream.h handleStream.I \
     handleStreamBuf.cxx handleStreamBuf.h \
     p3d_lock.h p3d_plugin.h \
+    p3d_plugin_config.h \
     p3d_plugin_common.h \
     p3dDownload.h p3dDownload.I \
     p3dFileDownload.h p3dFileDownload.I \
@@ -64,6 +65,7 @@
     handleStream.cxx handleStream.h handleStream.I \
     handleStreamBuf.cxx handleStreamBuf.h \
     p3d_lock.h p3d_plugin.h \
+    p3d_plugin_config.h \
     p3dCInstance.cxx \
     p3dCInstance.h p3dCInstance.I \
     p3dPythonRun.cxx p3dPythonRun.h p3dPythonRun.I
diff --git a/direct/src/plugin/load_plugin.cxx b/direct/src/plugin/load_plugin.cxx
index 45246a1f79..d59785ed08 100755
--- a/direct/src/plugin/load_plugin.cxx
+++ b/direct/src/plugin/load_plugin.cxx
@@ -15,6 +15,8 @@
 #include "load_plugin.h"
 #include "p3d_plugin_config.h"
 
+#include "assert.h"
+
 #ifndef _WIN32
 #include <dlfcn.h>
 #endif
@@ -62,6 +64,47 @@ get_plugin_basename() {
   return default_plugin_filename + dll_ext;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: is_pathsep
+//  Description: Returns true if the indicated character is a path
+//               separator character (e.g. slash or backslash), false
+//               otherwise.
+////////////////////////////////////////////////////////////////////
+static inline bool
+is_pathsep(char ch) {
+  if (ch == '/') {
+    return true;
+  }
+#ifdef _WIN32
+  if (ch == '\\') {
+    return true;
+  }
+#endif
+  return false;
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: find_extension_dot
+//  Description: Returns the position in the string of the dot before
+//               the filename extension; that is, the position of the
+//               rightmost dot that is right of the rightmost slash
+//               (or backslash, on Windows).  Returns string::npos if
+//               there is no extension.
+////////////////////////////////////////////////////////////////////
+static size_t
+find_extension_dot(const string &filename) {
+  size_t p = filename.length();
+  while (p > 0 && !is_pathsep(filename[p - 1])) {
+    --p;
+    if (filename[p] == '.') {
+      return p;
+    }
+  }
+
+  return string::npos;
+}
+
+
 ////////////////////////////////////////////////////////////////////
 //     Function: load_plugin
 //  Description: Loads the plugin and assigns all of the function
@@ -83,6 +126,18 @@ load_plugin(const string &p3d_plugin_filename) {
 
 #ifdef _WIN32
   assert(module == NULL);
+  
+  // On Windows, the filename passed to LoadLibrary() must have an
+  // extension, or a default ".DLL" will be implicitly added.  If the
+  // file actually has no extension, we must add "." to avoid this.
+
+  // Check whether the filename has an extension.
+  size_t extension_dot = find_extension_dot(filename);
+  if (extension_dot == string::npos) {
+    // No extension.
+    filename += ".";
+  }
+
   module = LoadLibrary(filename.c_str());
   if (module == NULL) {
     // Couldn't load the DLL.
diff --git a/direct/src/plugin/p3dSession.cxx b/direct/src/plugin/p3dSession.cxx
index ce59c67c51..113d1f5975 100644
--- a/direct/src/plugin/p3dSession.cxx
+++ b/direct/src/plugin/p3dSession.cxx
@@ -240,7 +240,7 @@ start_p3dpython() {
   if (p3dpython.empty()) {
     p3dpython = _python_root_dir + "/p3dpython";
 #ifdef _WIN32
-    p3dpython += ".exe"
+    p3dpython += ".exe";
 #endif
   }
 
diff --git a/direct/src/plugin/p3d_plugin_config.h.pp b/direct/src/plugin/p3d_plugin_config.h.pp
index 8e34fc8d83..f296ad1a23 100644
--- a/direct/src/plugin/p3d_plugin_config.h.pp
+++ b/direct/src/plugin/p3d_plugin_config.h.pp
@@ -13,12 +13,12 @@
 
 /* The filename(s) to generate output to when the plugin is running.
    For debugging purposes only. */
-#$[]define P3D_PLUGIN_LOGFILE1 "$[osfilename $[P3D_PLUGIN_LOGFILE1]]"
-#$[]define P3D_PLUGIN_LOGFILE2 "$[osfilename $[P3D_PLUGIN_LOGFILE2]]"
+#$[]define P3D_PLUGIN_LOGFILE1 "$[subst \,\\,$[osfilename $[P3D_PLUGIN_LOGFILE1]]]"
+#$[]define P3D_PLUGIN_LOGFILE2 "$[subst \,\\,$[osfilename $[P3D_PLUGIN_LOGFILE2]]]"
 
 /* Temporary: the location at which p3dpython.exe can be found.  Empty
    string for the default. */
-#$[]define P3D_PLUGIN_P3DPYTHON "$[osfilename $[P3D_PLUGIN_P3DPYTHON]]"
+#$[]define P3D_PLUGIN_P3DPYTHON "$[subst \,\\,$[osfilename $[P3D_PLUGIN_P3DPYTHON]]]"
 
 /* The string that corresponds to this particular platform. */
 #if $[not $[P3D_PLUGIN_PLATFORM]]
diff --git a/direct/src/plugin_npapi/ppInstance.cxx b/direct/src/plugin_npapi/ppInstance.cxx
index 34f04de713..408c0a0dab 100644
--- a/direct/src/plugin_npapi/ppInstance.cxx
+++ b/direct/src/plugin_npapi/ppInstance.cxx
@@ -47,14 +47,16 @@ PPInstance(NPMIMEType pluginType, NPP instance, uint16 mode,
   _got_instance_data = false;
   _got_window = false;
 
-  // Start the plugin DLL downloading.
-  string url = P3D_PLUGIN_DOWNLOAD;
-  url += P3D_PLUGIN_PLATFORM;
-  url += "/";
-  url += get_plugin_basename();
-
-  PPDownloadRequest *req = new PPDownloadRequest(PPDownloadRequest::RT_core_dll);
-  browser->geturlnotify(_npp_instance, url.c_str(), NULL, req);
+  if (!is_plugin_loaded()) {
+    // Start the plugin DLL downloading.
+    string url = P3D_PLUGIN_DOWNLOAD;
+    url += P3D_PLUGIN_PLATFORM;
+    url += "/";
+    url += get_plugin_basename();
+    
+    PPDownloadRequest *req = new PPDownloadRequest(PPDownloadRequest::RT_core_dll);
+    browser->geturlnotify(_npp_instance, url.c_str(), NULL, req);
+  }
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -211,6 +213,7 @@ stream_as_file(NPStream *stream, const char *fname) {
     if (!load_plugin(filename)) {
       logfile << "Unable to launch core API.\n";
     }
+    create_instance();
     break;
 
   case PPDownloadRequest::RT_instance_data:
diff --git a/direct/src/plugin_npapi/startup.cxx b/direct/src/plugin_npapi/startup.cxx
index da0571cca1..4039c7e4f1 100644
--- a/direct/src/plugin_npapi/startup.cxx
+++ b/direct/src/plugin_npapi/startup.cxx
@@ -194,7 +194,7 @@ NPP_NewStream(NPP instance, NPMIMEType type, NPStream *stream,
   PPInstance *inst = (PPInstance *)(instance->pdata);
   assert(inst != NULL);
 
-  return inst->new_stream(type, stream, seekable, stype);
+  return inst->new_stream(type, stream, seekable != 0, stype);
 }
 
 ////////////////////////////////////////////////////////////////////