B5, XPSP2, MBP Every time after an energy-saver-timeout induced sleep, VM is frozen, Parallels must eventually be Forced to Quit. I did notice that if I put the computer to sleep manually from the system menu, wait for everything to spin down, then wake it up, VM does not hang, if that helps. Not sure if that would still be the case after a long time, though I don't know why that should matter.
The freeze problem persists for me as well in beta 5. I noticed the same thing as richh with regards to it not freezing with a brief manual sleep, I think this was the case in Beta 4 as well. Setting sleep to never does seem to solve the problem, but it is not a good long term solution. MBP, Win XP SP2, Beta 5
I did a manual sleep and left it sleeping for about 45 minutes and XP is not frozen. Not sure why a manual sleep would behave differently than an energy saver sleep.