I have multiple Ubuntu systems connected to a KVM, one of which I recently upgraded from Ubuntu 10 to 12.04.

After the upgrade, this system desktop does fine until it is allowed to go to idle (i.e., I've switched to another system on the KVM and it locks it's desktop). When I come back to it, the screen is garbled and paging across at a rate seemingly determined by the mouse. Although no pointer is visible, I can get the screen to stop paging (and just be garbled) by moving the mouse left and right.

The paging will slow down and come to a stop, if I can align things carefully enough. This condition persists even when I try to go to a CLI-based login (e.g., CTRL+Alt+F1) and will continue until I reboot the machine.

Unfortunately, I'm not very familiar with the Unity desktop, so I don't know where to find things to troubleshoot. A restart of lightdm doesn't change anything, so I'm wondering if this might be more hardware based( although this machine hasn't given me any trouble previously in the same setup). The .xsession-errors file has some issues with compiz, nautilus and GConf listed, but I'm not sure those are actually germane to the issue.

Thanks for any help,

-=Tom