Increase the RAM to your VM. Photoshop is memory HOG and use 768MB all by itself. I ran into the same issues and increased my VM RAM to 1.5GB and the problems went away.
Also from a side note, Adobe will not support Photoshop running within a VM since they have not tested it. I tried and they denied helping me. Just something to know. If you call them do not tell them you are using within a VM or on a Mac.
Last edited: Oct 12, 2007