I confirm this bug with an nvidia Geforce FX 5200 running the latest proprietary video drivers in Dapper. I've found the easiest way to fix it is hit CTRL ALT Arrow key to spin the cube.
The problem is that Xgl doesn't repaint the desktop or anything after the screensaver deactivates so everything looks very strange and takes awhile to repaint everything. This could be problems with one or all three of: - the nvidia drivers - gnome-screensaver - gtk -- gnome-screensaver doesn't always stop https://launchpad.net/bugs/38644 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
