How to prevent flash crashes in Firefox
From version 3.6.4 Firefox started to use plugin-container.exe as external container over browser plugins in general and flash player specifically
This to prevent browser crashes in case of plugin crash. The idea is nice, the implementation caused to common plugins instability.
In cases when plugin is "hard-working" (and Flash is good candidate), the communication between browser and plugin-container can be lost. In that cases FF counts till 45 and kills the plugin, sometimes it causes to FF freeze also.
There are 2 workarounds - return to version 3.6.3 or disable "plugin-container" feature in FF about:config (search for "ipc" string):
dom.ipc.plugins.enabled = true
dom.ipc.plugins.enabled.npctrl.dll = false
dom.ipc.plugins.enabled.npqtplugin.dll = false
dom.ipc.plugins.enabled.npswf32.dll = false
dom.ipc.plugins.enabled.nptest.dll = false
*It's better to disable FF updates also, till Mozilla will fix it