A currently installed Ubuntu 12.04 will leave my IBM X30 with a black screen after resuming from sleep mode. It seems as if the machine itself would return, but only the screen remains black and without backlight.
The problem does not occur on an identically installed X40.
I'm not sure if it's the same issue, but i've had a situation like this on a laptop with intel graphics. The problem in my case was the computer resumed (no issues in dmesg or other logs), and the graphics was on (if you looked really close there was an image on the screen), it just didn't turn on the backlight (some hardware issue as i've later found out).
In my situation the solution was just to press brightness down/up a few times.
I know it's a silly solution but it worked for me. I could then automate the process by adding a script to the resume script chain that changed the brightness down/up.
/var/log/kern.log, command(s):dmesg– ish Aug 13 '12 at 01:34