Internetworkers: http://www.ibiblio.org/internetworkers/

["Cristobal Palmer" <cristobalpalmer AT gmail.com>]

My money is on a driver. Dig out the recovery CD that came with the
bundle and re-install the video card driver. The driver may have been
corrupted in any number of ways.

Let us know if re-installing the driver fails. I've seen monumentally
weird stuff happen with a flaky PSU, so I wouldn't rule out a hardware
issue entirely based on the description.

Best of luck,

--
Cristobal M. Palmer
UNC-CH SILS Student -- ils.unc.edu/~cmpalmer
TriLUG Vice Chair
"There are many roads to enlightenment, and thus many roads back to
the One True Debian" --crimsun