Something strange happened a few days ago that I have now tracked down and corrected.
I use a ATi XTX1950X 512mb video card on my Vista workstation with the Catalyst control center software to configure it.
One day I noticed that my monitor didn’t look right and when I checked it read 85 candelas instead of 100. I re calibrated but 2 sets of calibration software couldn’t achieve a brightness level higher than 85. This is the kind of behaviour to expect from a 5 year old CRT monitor and not a CG211 LCD panel less than one year old.
When I attached my Mac to the screen however I found the brightness back to expected levels so it wasn’t the screen.
I knew therefore it was the PC setup at fault and proceeded to check everything, including uninstalling and reinstalling the ATI drivers and Catalyst program.
Eventually I traced the problem to an obscure setting in the color panel of the Catalyst control center. It was set on “PC standard black and white levels” which sounds fine to me but when I changed it to “Microsoft MCE black and white levels” I got my display brightness back. I have no recollection of even seeing this setting before so I’m unclear as to how the change happened.
I’m mentioning it here so anyone else who comes across this problem knows how to fix it. I seem to get a lot of hits from Google searches from people with imaging related problems, nice to know I’m helping!