Thanks gonk.

I'll try just unplugging the DVI cable that's connected from my PC to the TV to see if I get the same behaviour.

Any thoughts on whether on not an HDMI receiver/processor would exibit this same behaviour?

EDIT - Looks like it's an issue with HDMI receivers as well. Maybe there'll be an eventual update to the video card drivers to support forcing DualView on.
http://www.avsforum.com/avs-vb/showthread.php?t=1108334

-John