Lisa, blue screen, cannot change wallpaper how to fix

[MVCTplus]

I have been using mint 12 lisa for about a week, installed on a virtual machine, and started up today, and my wallpaper and gnome classic launchers are gone, and no longer function. I cannot change the wallpaper, add launchers, and when I print scree, it will only print the blue screen and mouse. Anybody have an idea how I might be able to fix this?