My wife has an Apple Cinema HD 30" display connected to MacPro (2008 model). Recently, the resolution of the monitor dropped and only 1260x800 or lower are showing in the preference pane. It runs 10.6.6. I could not locate the display preferences in the User folder/library/preferences to try to trash it. Just for the record, the computer has a USB bluetooth module to connect to an Apple Bluetooth magic mouse. Zooming with mouse is turned off, as well as VoiceOver. The computer was moved today to a new location and it was unplugged for 15-20 minutes, which would reset the SMC. Should I reset the PRAM?
Thanks for any input.

Display resolution is stored in PRAM so resetting it might help and it certainly won't hurt.

Thanks a lot, will try.

Resetting the PRAM (I even waited for two restarts) did not work. Changing the port (this model has two DVI ports) did the trick. All resolutions are back. My first with a port problem...