Thought I'd post his for anyone else that comes across this issue. Sadly no solution.
I run a 42" Vizio HDTV 1920x1080 off my laptop, an ATI 5870 Mobile over HDMI.
Ever since the preview drivers
for 11.10 and 11.10 themselves, the HD display is over scanned to where you can't see the edges of screen, the controls are grayed out and the slider is maxed which explains the overscan. Changing the resolution to 1280x720 brings back control and puts the slider back to the middle normal position. The laptop display is fine. Rolling back to 11.9 makes everything good again.
Have tried uninstalls, cleaning, plug unplug, etc. Nothing works. It really just looks like they broke the functionality in the driver
. I've only run across a couple of others that have the same issue and it's with the 11.10 drivers. Put in a ticket to AMD but not holding my breath.