I just installed Backtrack 5 Gnome x64 version. Along with it i installed AMD ATI official drivers from their site for my ATI 5770, and i installed compiz and pidgin.
The problem is i don't remember if the bug existed before installing any of these applications, but now when i move my cursor in the area of workspaces/trash and a little above it everything seems normal, but when i try to move the cursor out of that "invisible" box every freezes for about 1, 2 seconds and my CPU load rises.
I checked the system monitor and it rises for about 75% on one core (i have AMD Phenom II x4 955 BE) core 3 or core 4, may be even the first two but wasn't patient enough to check. This CPU load stands only for the duration of the freeze which is 1, 2 seconds.