I'm running VMware Workstation 7.1.5 64-bit on a Windows 7 host (48GB RAM), with Ubuntu 11.04 Natty Narwhal 64-bit as a guest (24GB RAM). For some reason, X crashes semi-regularly in my guest OS. I think it always happens while I'm typing, and I get the feeling it almost(?) always happens when I hit enter. Gdm is automatically restarted, and when I log in again, everything is ok, except that after a while my windows theme gets screwed up, and all the windows look really old. I've never experienced a new crash in this state, however. If I reboot the guest, the theme looks good again, but then it's just a matter of time until X crashes again.
Anyone else experienced this?