FF4 hangs on windows vista and win7

Hi,

I am a developer of Adobe Toolbar plugin for firefox4 and I am facing
some problem on FF4 windows vista/win7. I have built the plugins for
mac and windows. Plugin is working correctly on windows xp and all
flavors of mac(i.e 10.5, 10.6 and 10.7) but it not working on windows
vista and win7. When I open plugin on windows vista/win7 it loads and
unloads successfully but after unloading the plugin instance from
NPP_Destroy() FF4 hangs in xul.dll and we have to forcefully kill the
firefox.exe from task manager. We are getting “one or more arguments
are invalid” exception  in KiFastSystemCallRet(). Module name is XUL
and faulting module is ntdll.

Also, after analyzing with SPY++ tool, I have noticed that my plugin's
window handler is properly exiting from the Firefox window and after
that Firefox window handler is going in infinite loop with WM_PAINT
message(<006A0C9C P WM_PAINT hdc:00000000>). Kindly tell what could be
the reason for this behavior?

I tried to set “dom.ipc.plugin.enabled” setting in configuration file
as false but it did not work.

Any pointer in this direction would be of great help.

Thanks in advance,
Pooja Dixit,
Adobe Systems