Hmm, interesting. I just came across this in my kernel log:
Oct 20 09:27:50 bruce-desktop kernel: [ 288.987659] Disabling lock
debugging due to kernel taint
Oct 20 09:27:50 bruce-desktop kernel: [ 289.585883] NVRM: The NVIDIA
probe routine was not called for 1 device(s).
Oct 20 09:27:50 bruce-desktop kernel: [ 289.585886] NVRM: This can
occur when a driver such as rivafb, nvidiafb or
Oct 20 09:27:50 bruce-desktop kernel: [ 289.585887] NVRM: rivatv was
loaded and obtained ownership of the NVIDIA
Oct 20 09:27:50 bruce-desktop kernel: [ 289.585888] NVRM: device(s).
Oct 20 09:27:50 bruce-desktop kernel: [ 289.585890] NVRM: Try unloading
the rivafb, nvidiafb or rivatv kernel module
Oct 20 09:27:50 bruce-desktop kernel: [ 289.585891] NVRM: (and/or
reconfigure your kernel without rivafb/nvidiafb
Oct 20 09:27:50 bruce-desktop kernel: [ 289.585892] NVRM: support),
then try loading the NVIDIA kernel module again.
Oct 20 09:27:50 bruce-desktop kernel: [ 289.585894] NVRM: No NVIDIA
graphics adapter probed!

What does all this mean? I did do a re-install of Ubuntu 64 bit myself,
and am using the Nvidia proprietary driver.