After feeling myself very miserable, because VMWare Player was "crashing" after trying to play any virtual machine on Ubuntu 11.04 ("crashing in the sense that it was still running in the background, but the screen was gone), I accidentally found some helpful info where somebody with the similar problem mentioned that he had to downgrade overlay-scrollbar package from version 0.1.9 to 0.1.7.
This solution didn't work for me (because I had fresh Ubuntu 11.04 install), but after starting Synaptic Package Manager, I could see that there is a newer version of overlay-scrollbar package available (0.1.12) and decided to give it a try. Miracle happened - VMWare Player started to work normally after I performed the upgrade. (It took several hours of trying to find out what was happening, and I strongly dislike those new fancy scrollbars - now even more so!.. :) )
PS I have also found one other mentioning of VMWare problem with the latest Ubuntu here, but their solution didn't seem to help.