For a number of releases I've been seeing my XP VM lock up when I go to lunch or something after the screen saver kicks in... I can't "Send ctrl-alt-del" or get the machine back by clicking in the window. I have to kill it with the activity manager because forcing a power down doesn't work either... has anyone else experienced this? Is there more information I can provide to help you guys fix this problem?
I don't quite know if this is associated, but I deleted my CDROM drive in the property page view and that's when i started to notice this problem. When I readded the hardware, the crashing stopped. I guess it needs the CDROM to operate properly. Maybe this is the same issue for you?