Computer freezes when minimizing programs

Sometimes when I minimize programs windows will sort of freeze, music will keep playing, but it won't advance to the next track and it doesn't respond to keyboard commands and the mouse curser will continue to move unless I start clicking and then it stops and beeps at me once and I can ping it, but not remote desktop into it or anything.
This happens on both OSes I have installed (dual botting XP and XP X64)
The system is completely stable otherwise, even overclocked to 2.4 ghz for cpu and 510/1159 for 7800GT.
And before you ask it happens at stock speeds also.


3200+ winchester
MSI neo4-F
512DDR XMS 3200C2
512DDR pny 3200 (not the problem.. tried just one corsair stick)
7800GT
and a uh.. allied 500watt psu.. wasn't my choice, it was to replace my 420 watt noisetaker 1.3 that would shut off randomly.

Go to system properties (windows key + pause break) choose the advanced tab, and press the Settings button under the Performance area(top button). Uncheck the first option in the list"animate minimize and max". If that does not help then click the radio button that says "adjust for best performance" and see if that's better.

Well it hasn't locked up at all today so far and I've minimized a bunch of check.
So why would the animation cause it to lock?