I am not the only one who has suffered this problem, and despite the fact that there is a work around, the best advice I can offer, is that if you use a TV as your main display then save yourself a lot of trouble and hold off on the update.

To get an idea of the problem, have a look at the following thread (240 posts and counting) on the Apple discussion forums. There are several workarounds mentioned in the forums, but I couldn’t find any references to my particular TV. So after much trial and error, this is the solution I used.

Computer: MacMini
TV: Sony Bravia KDL-26T3000

Download a copy of SwitchResX. There is a trial version, so if the solution works, you should consider purchasing it. The process is simple, use SwitchResX to add your TV’s resolution to the list shown in Display Preferences and then Reboot. When your computer has restarted, use Display Preferences to select your new resolution.

The difficult part is finding the right resolution/timing settings for your TV. It took me some considerable time to find a setting that worked for the Sony Bravia KDL-26T3000 so I thought I’d share the settings below.

Have you suffered as a result of the upgrade to 10.5.7? Feel free to share your experiences in the comments.