This has actually been going on for a while for me but not often enough to really bother me. I play games mostly fullscreen @ 1920x1080p and My sytem specs:
Radeon HD 5870 (XFX)
4G of G Skill DD3 1600 Ram
Phenom II Black Edition 4 Core (3.4 Ghz)
OS Windows 7 64-bit
M4A785TD-V Evo Motherboard
The games vary so I know its not the games that I play and the symptoms happen when i try to minimize to look at something on my off screen running a extended 1280-1025 LCD Screen. Obviously with mid range spec pcs a minimize usually takes between instant-1sec to fully minimize maximize but i notice sometimes It takes 6-10s and I notice my ventrilo cuts out while im minimizing/maximizing. Im noticing a poorer framerate when these symptoms appear and its usually fixed by a hard reset.....does anyone have this issue?