blacked out screen on Suse 11.1 under vmware workstation 6

I’m using Suse 11.1 under VMware Workstation 6 (on a Windows XT machine). Occasionally my screen turns almost completely black (actually, I can see a pattern, but it’s very faint). After a few boots the problem will generally fix itself, but I would like to fix it quicker. Does anybody know how?