diff --git a/direct/src/plugin/p3dInstance.cxx b/direct/src/plugin/p3dInstance.cxx
index 409778291b..c03a8be387 100644
--- a/direct/src/plugin/p3dInstance.cxx
+++ b/direct/src/plugin/p3dInstance.cxx
@@ -108,6 +108,10 @@ P3DInstance(P3D_request_ready_func *func,
   _allow_python_dev = false;
   _keep_user_env = (_fparams.lookup_token_int("keep_user_env") != 0);
   _auto_start = (_fparams.lookup_token_int("auto_start") != 0);
+  _auto_install = true;
+  if (_fparams.has_token("auto_install")) {
+    _auto_install = (_fparams.lookup_token_int("auto_install") != 0);
+  }
   _auth_button_clicked = false;
   _failed = false;
   _session = NULL;
@@ -119,6 +123,7 @@ P3DInstance(P3D_request_ready_func *func,
   _download_package_index = 0;
   _total_download_size = 0;
   _total_downloaded = 0;
+  _download_started = false;
   _download_complete = false;
   
   INIT_LOCK(_request_lock);
@@ -486,7 +491,7 @@ set_wparams(const P3DWindowParams &wparams) {
     _session->send_command(doc);
   }
 
-  if (get_packages_ready() && _p3d_trusted) {
+  if (_p3d_trusted && get_packages_ready()) {
     ready_to_start();
   }
 }
@@ -1272,9 +1277,17 @@ void P3DInstance::
 play_button_clicked() {
   if (_session == NULL && _p3d_trusted) {
     set_button_image(IT_none);
-    set_background_image(IT_launch);
-    P3DInstanceManager *inst_mgr = P3DInstanceManager::get_global_ptr();
-    inst_mgr->start_instance(this);
+    if (!_download_started) {
+      // Now we initiate the download.
+      _auto_install = true;
+      _auto_start = true;
+      ready_to_install();
+
+    } else {
+      set_background_image(IT_launch);
+      P3DInstanceManager *inst_mgr = P3DInstanceManager::get_global_ptr();
+      inst_mgr->start_instance(this);
+    }
   }
 }
 
@@ -1326,6 +1339,7 @@ auth_finished_main_thread() {
 void P3DInstance::
 uninstall() {
   if (_session != NULL) {
+    _session->set_failed();
     _session->shutdown();
   }
 
@@ -1333,7 +1347,13 @@ uninstall() {
   for (pi = _packages.begin(); pi != _packages.end(); ++pi) {
     P3DPackage *package = (*pi);
     package->uninstall();
+    package->remove_instance(this);
   }
+  _packages.clear();
+
+  _auto_install = false;
+  _instance_window_opened = false;
+  set_failed();
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -1706,6 +1726,8 @@ mark_p3d_trusted() {
   // Only call this once.
   assert(!_p3d_trusted);
 
+  _p3d_trusted = true;
+
   // Extract the application desc file from the p3d file.
   stringstream sstream;
   if (!_mf_reader.extract_one(sstream, "p3d_info.xml")) {
@@ -1717,8 +1739,6 @@ mark_p3d_trusted() {
     TiXmlDocument doc;
     sstream >> doc;
 
-    // This also starts required packages downloading.  When all
-    // packages have been installed, we will start the instance.
     scan_app_desc_file(&doc);
   }
 
@@ -1732,19 +1752,14 @@ mark_p3d_trusted() {
   strm << inst_mgr->get_unique_id();
   _session_key = strm.str();
 
-  // Until we've done all of the above processing, we haven't fully
-  // committed to setting the trusted flag.  (Setting this flag down
-  // here instead of a few lines above avoids starting the instance in
-  // scan_app_desc_file(), before we've had a chance to finish
-  // processing this method.)
-  _p3d_trusted = true;
-
   // Notify JS that we've accepted the trust of the p3d file.
   _panda_script_object->set_bool_property("trusted", true);
   send_notify("onauth");
 
-  // Now that we're all set up, start the instance if we're already
+  // Now that we're all set up, start downloading the required
+  // packages, and then start the instance itself if we're already
   // fully downloaded.
+  add_packages();
   if (get_packages_ready()) {
     mark_download_complete();
   }
@@ -1815,6 +1830,11 @@ scan_app_desc_file(TiXmlDocument *doc) {
     if (xconfig->QueryIntAttribute("auto_start", &auto_start) == TIXML_SUCCESS) {
       _auto_start = (auto_start != 0);
     }
+
+    int auto_install = 0;
+    if (xconfig->QueryIntAttribute("auto_install", &auto_install) == TIXML_SUCCESS) {
+      _auto_install = (auto_install != 0);
+    }
   }
 
   nout << "_matches_run_origin = " << _matches_run_origin << "\n";
@@ -1831,15 +1851,36 @@ scan_app_desc_file(TiXmlDocument *doc) {
     // But finally, if the user has already clicked through the red
     // "auth" button, no need to present him/her with another green
     // "play" button as well.
+    _auto_install = true;
     _auto_start = true;
   }
 
-  nout << "_auto_start = " << _auto_start << "\n";
+  nout << "_auto_install = " << _auto_install 
+       << ", _auto_start = " << _auto_start << "\n";
 
   if (_hidden && _got_wparams) {
     _wparams.set_window_type(P3D_WT_hidden);
   }
 
+  if (!_matches_run_origin) {
+    nout << "Cannot run " << _p3d_basename << " from origin " 
+         << _origin_protocol << "//" << _origin_hostname
+         << ":" << _origin_port << "\n";
+    set_failed();
+  }
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: P3DInstance::add_packages
+//       Access: Private
+//  Description: Adds the set of packages required by this p3d file to
+//               the _packages member.  If _auto_install is true, this
+//               will also start downloading them.
+////////////////////////////////////////////////////////////////////
+void P3DInstance::
+add_packages() {
+  P3DInstanceManager *inst_mgr = P3DInstanceManager::get_global_ptr();
+
   TiXmlElement *xrequires = _xpackage->FirstChildElement("requires");
   while (xrequires != NULL) {
     const char *name = xrequires->Attribute("name");
@@ -1855,15 +1896,9 @@ scan_app_desc_file(TiXmlDocument *doc) {
 
     xrequires = xrequires->NextSiblingElement("requires");
   }
-
-  if (!_matches_run_origin) {
-    nout << "Cannot run " << _p3d_basename << " from origin " 
-         << _origin_protocol << "//" << _origin_hostname
-         << ":" << _origin_port << "\n";
-    set_failed();
-  }
 }
 
+
 ////////////////////////////////////////////////////////////////////
 //     Function: P3DInstance::find_alt_host_url
 //       Access: Private
@@ -2270,7 +2305,7 @@ make_splash_window() {
   }
 
   if (_wparams.get_window_type() != P3D_WT_embedded && 
-      !_stuff_to_download && _auto_start && _p3d_trusted) {
+      !_stuff_to_download && _auto_install && _auto_start && _p3d_trusted) {
     // If it's a toplevel or fullscreen window, then we don't want a
     // splash window unless we have stuff to download, or a button to
     // display.
@@ -2514,41 +2549,59 @@ report_package_info_ready(P3DPackage *package) {
         _total_download_size += package->get_download_size();
       }
     }
-    if (_downloading_packages.empty() && _download_complete) {
-      // We have already been here.  Ignore it.
-
-    } else {
-      _download_complete = false;
-      _download_package_index = 0;
-      _total_downloaded = 0;
-      _download_begin = time(NULL);
-      
-      nout << "Beginning install of " << _downloading_packages.size()
-           << " packages, total " << _total_download_size
-           << " bytes required.\n";
-      
-      if (_downloading_packages.size() > 0) {
-        _stuff_to_download = true;
-        
-        // Maybe it's time to open a splash window now.
-        make_splash_window();
-      }
-      
-      if (_splash_window != NULL) {
-        _splash_window->set_install_progress(0.0, true, 0);
-      }
-      _panda_script_object->set_string_property("status", "downloading");
-      _panda_script_object->set_int_property("numDownloadingPackages", _downloading_packages.size());
-      _panda_script_object->set_int_property("totalDownloadSize", _total_download_size);
-      _panda_script_object->set_int_property("downloadElapsedSeconds", 0);
-      _panda_script_object->set_undefined_property("downloadRemainingSeconds");
-      send_notify("ondownloadbegin");
-      
-      start_next_download();
-    }
+    ready_to_install();
   }
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: P3DInstance::ready_to_install
+//       Access: Private
+//  Description: Called when it's time to start the package download
+//               process.
+////////////////////////////////////////////////////////////////////
+void P3DInstance::
+ready_to_install() {
+  if (_downloading_packages.empty() && _download_complete) {
+    // We have already been here.  Ignore it.
+    
+  } else if (!_auto_install && !_download_started) {
+    // Not authorized to download yet.  We're waiting for the user
+    // to acknowledge the download.
+    set_background_image(IT_ready);
+    set_button_image(IT_play_ready);
+    
+  } else {
+    _download_started = true;
+    _download_complete = false;
+    _download_package_index = 0;
+    _total_downloaded = 0;
+    _download_begin = time(NULL);
+    
+    nout << "Beginning install of " << _downloading_packages.size()
+         << " packages, total " << _total_download_size
+         << " bytes required.\n";
+    
+    if (_downloading_packages.size() > 0) {
+      _stuff_to_download = true;
+      
+      // Maybe it's time to open a splash window now.
+      make_splash_window();
+    }
+    
+    if (_splash_window != NULL) {
+      _splash_window->set_install_progress(0.0, true, 0);
+    }
+    _panda_script_object->set_string_property("status", "downloading");
+    _panda_script_object->set_int_property("numDownloadingPackages", _downloading_packages.size());
+    _panda_script_object->set_int_property("totalDownloadSize", _total_download_size);
+    _panda_script_object->set_int_property("downloadElapsedSeconds", 0);
+    _panda_script_object->set_undefined_property("downloadRemainingSeconds");
+    send_notify("ondownloadbegin");
+    
+    start_next_download();
+  }
+}
+  
 ////////////////////////////////////////////////////////////////////
 //     Function: P3DInstance::start_next_download
 //       Access: Private
@@ -2645,7 +2698,7 @@ ready_to_start() {
     P3DInstanceManager *inst_mgr = P3DInstanceManager::get_global_ptr();
     inst_mgr->start_instance(this);
 
-  } else if (_splash_window != NULL) {
+  } else {
     // We're fully downloaded, and waiting for the user to click play.
     set_background_image(IT_ready);
     set_button_image(IT_play_ready);
diff --git a/direct/src/plugin/p3dInstance.h b/direct/src/plugin/p3dInstance.h
index b52e295074..4f8c20fe10 100644
--- a/direct/src/plugin/p3dInstance.h
+++ b/direct/src/plugin/p3dInstance.h
@@ -171,6 +171,7 @@ private:
   void mark_p3d_untrusted();
   void mark_p3d_trusted();
   void scan_app_desc_file(TiXmlDocument *doc);
+  void add_packages();
   string find_alt_host_url(const string &host_url, const string &alt_host);
   void get_host_info(P3DHost *host);
 
@@ -186,6 +187,7 @@ private:
   void set_background_image(ImageType image_type);
   void set_button_image(ImageType image_type);
   void report_package_info_ready(P3DPackage *package);
+  void ready_to_install();
   void start_next_download();
   void mark_download_complete();
   void ready_to_start();
@@ -263,6 +265,7 @@ private:
   bool _matches_script_origin;
   bool _allow_python_dev;
   bool _keep_user_env;
+  bool _auto_install;
   bool _auto_start;
   bool _auth_button_clicked;
   bool _failed;
@@ -306,6 +309,7 @@ private:
   size_t _total_download_size;
   size_t _total_downloaded;
   time_t _download_begin;
+  bool _download_started;
   bool _download_complete;
 
   // We keep the _panda3d pointer separately because it's so
diff --git a/direct/src/plugin/p3dPackage.cxx b/direct/src/plugin/p3dPackage.cxx
index ba8621006e..91c235c570 100755
--- a/direct/src/plugin/p3dPackage.cxx
+++ b/direct/src/plugin/p3dPackage.cxx
@@ -116,10 +116,6 @@ P3DPackage::
 ////////////////////////////////////////////////////////////////////
 void P3DPackage::
 activate_download() {
-  if (_allow_data_download) {
-    // Already activated.
-  }
-
   _allow_data_download = true;
 
   if (_ready) {
@@ -243,11 +239,10 @@ uninstall() {
     }
   }
 
-  // Now delete all of the directories too.  Go in reverse order so we
-  // remove deeper directories first.
-  vector<string>::reverse_iterator rci;
-  for (rci = dirname_contents.rbegin(); rci != dirname_contents.rend(); ++rci) {
-    string filename = (*rci);
+  // Now delete all of the directories too.  They're already in
+  // reverse order, so we remove deeper directories first.
+  for (ci = dirname_contents.begin(); ci != dirname_contents.end(); ++ci) {
+    string filename = (*ci);
     string pathname = _package_dir + "/" + filename;
 
 #ifdef _WIN32
@@ -276,6 +271,7 @@ uninstall() {
   _info_ready = false;
   _ready = false;
   _failed = false;
+  _allow_data_download = false;
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -514,7 +510,7 @@ contents_file_redownload_finished(bool success) {
 //               rest of the download process.
 ////////////////////////////////////////////////////////////////////
 void P3DPackage::
-host_got_contents_file(bool continue_download) {
+host_got_contents_file() {
   if (!_alt_host.empty()) {
     // If we have an alt host specification, maybe we need to change
     // the host now.
@@ -548,23 +544,22 @@ host_got_contents_file(bool continue_download) {
     _package_dir += string("/") + _package_version;
   }
 
-  if (continue_download) {
-    // Ensure the package directory exists; create it if it does not.
-    mkdir_complete(_package_dir, nout);
-    
-    download_desc_file();
-  }
+  // Ensure the package directory exists; create it if it does not.
+  mkdir_complete(_package_dir, nout);
+  download_desc_file();
 }
 
 ////////////////////////////////////////////////////////////////////
 //     Function: P3DPackage::download_desc_file
 //       Access: Private
 //  Description: Starts downloading the desc file for the package, if
-//               it's needed; or read to local version if it's fresh
+//               it's needed; or read the local version if it's fresh
 //               enough.
 ////////////////////////////////////////////////////////////////////
 void P3DPackage::
 download_desc_file() {
+  assert(!_package_dir.empty());
+
   // Attempt to check the desc file for freshness.  If it already
   // exists, and is consistent with the server contents file, we don't
   // need to re-download it.
diff --git a/direct/src/plugin/p3dPackage.h b/direct/src/plugin/p3dPackage.h
index 1343a5223e..72f6b70f8f 100755
--- a/direct/src/plugin/p3dPackage.h
+++ b/direct/src/plugin/p3dPackage.h
@@ -194,7 +194,7 @@ private:
   void contents_file_download_finished(bool success);
   void redownload_contents_file(Download *download);
   void contents_file_redownload_finished(bool success);
-  void host_got_contents_file(bool continue_download = true);
+  void host_got_contents_file();
 
   void download_desc_file();
   void desc_file_download_finished(bool success);