It's out of this topic, but let's hope others will excuse: My problem was when trying to upgrade to ATI Catalyst 7.10 for ATI Radeon X800 card. It displayed some warning at the beginning of uninstallation, but I was unable to read it. (It's necessary to completely remove all ATI software first, they say.) After first reboot it still ran in the same video mode, while it should run in some basic one and on a single monitor only. I finished the installation anyway thus creating quite unstable system with many strange symptoms. Then I realized that I should start all over. The second attempt went okay and it's still running good.
The painful part is that you have to set everything from scratch, recalibrate monitors, install Hydravision (if you need it, but I do, unfortunately) and set up again all the keyboard shortcuts. Also, QTTabBar stopped working. So you have to uninstall it, and reinstall again. Fortunately I've recently discovered how to save and restore
its settings, which saves a lot of time.
In short, if everything goes well, it takes at least four restarts and some superfluous work just to update video driver and its bloated suite.