Dell PoweEdge 1600SC
ATI Radeon HD 2400 Pro 256MB PCI graphics adaptor
Ubuntu 9.10 "Karmic Koala"
Linux 2.6.31-22-generic #69-Ubuntu SMP Wed Nov 24 08:51:08 UTC 2010 i686
ATI fglrx drivers
Set up for dual-head display using two Princeton 19" monitors
Using the Gnome desktop and screensaver
At some point, I suspect since the last kernel upgrade, I've begun experiencing a problem when the screen locks: I tap a key on the keyboard and the monitors wake up, but I get no "unlock" dialog. I can usually Ctrl-Alt-F1, login and gracefully reboot the system, but sometimes I have to hit hard reset.
Any clues on what's causing this and how I can fix it? For now I've disabled the screensaver in "System -> Preferences -> screensaver" (I assume that'll stop the problem), but that's not an optimal solution.