I'm stuck! I moved the brightness slider control to zero inside the Catalyst control software, and now the screen is so dark, I can't see *anything*. (I have tried using the monitor's brightness settings, but I still can't see anything.) The only way I can use my PC now is to abandon the HDMI cable, and use a DVI cable. I've uninstalled all ATI software, and reinstalled it, but as soon as the reinstallation has completed, the screen goes black again, because I guess it's using my old accidental "zero brightness" setting - perhaps from the system registry?
Does anyone know how I can set my brightness level to a normal value again, when using an HDMI cable? I wonder if it's a registry entry value/setting that I could change, using a RegEdit piece of software?
Thanks a lot for any suggestions! 
