You don't say anything about what OSs you are running - host and guest?
When mine does this, I need to set the screen resolution to the native resolution of my monitor - works great.
Host and Guest Systems:
Windows XP Pro x64 Edition;
VMware Server 2.0.0RC2, Build 110949
Have you got VMware tools installed in the guest virtual machine? This certainly helps with screen related issues with Windows guests.
i'm sorry if i didn't say anything about my guest and host OS, you were right. Anyway i found the solution setting the right screen resolution of host OS, and everything works great!
Thank you to all !!!