:dex:,

look at the memory usage of your processes in the taskmanager.

http://windows.microsoft.com/en-CA/windows-vista/Why-are-some-visual-elements-being-automatically-turned-off

[quote="Patrick"]If you have some spare time, disable all those add-ons, restart Firefox and test whether the problem still occurs. :wink:[/quote]

OK, yet another issue: I use Dexpot about 2 years, but since about May 2011 I regularly see this warning:

windows
"Do you want to change the color scheme to improve performance?
The current color scheme. windows Aero, is using most of its dedicated memory, which can result in slower computer performance. To free up some memory for better computer performance, try closing some open windows or changing the color scheme to Windows 7 Basic.
-Keep the current color scheme
-Change the color scheme to windows 7 "

If you have some spare time, disable all those add-ons, restart Firefox and test whether the problem still occurs. :wink:

[quote="Patrick"]Which version of Firefox do you use? Do you have any Firefox extensions installed?[/quote]

Firefox 5.0 + 20 Add-ons.
Hint: if immediately after returning from hibernate user press ALT-TAb trying to switch to those Firefox windows then they disappear, but in other case (make other desktop active + return back + ALT-TAb ) they do not disappear.

Which version of Firefox do you use? Do you have any Firefox extensions installed?

[quote="Sebastian"]:dex:,

[url=http://dexpot.de/forum/viewtopic.php?f=21&t=1848][FAQ] Some windows appearing on all desktops on Vista/7[/url][/quote]

OK, another case:
After returning from hibernate all Firefox windows copy yourself to desktop which was active in hibernate time.

:dex:,

[url=http://dexpot.de/forum/viewtopic.php?f=21&t=1848][FAQ] Some windows appearing on all desktops on Vista/7[/url]

Windows 7
If I start a program in compatibility mode it copy itself to all desktops. The same effect if I start it as administrator.