Sometimes some windows appear on two different desktops. Closing one window closes others.
Still don't see the system. Supposedly it happens when I change an active desktop during opening an application.

Aero theme've done magic)

The full-screen preview (Win+F3) on my PC is not "active": I can not move windows between desktops, can not choose "tale view" of opened windows pressing right mouse button or a wheel. And desktops don't show active content, just screenshots of their last state. The only possible...