I found a workaround that works for me. This only works for nvidia-cards.
The problem I appear to have is also discussed here for 10.04:
http://ubuntuforums.org/showthread.php?t=1476693.
The problem for nvidia in my case is the 'PowerMizer' feature that is
found on laptops using nvidia-drivers.
Got the same problem after a fresh install of kubuntu 11.10 x64.
Also, and likely related, I cannot access any virtual terminal using
Ctrl+Alt+F[1-6]. I just get a black screen, but I can resume the first
graphical X session by pressing Ctrl+Alt+F7.
Using an HP Elitebook8530w with a Nvidia
