resolution stuck

My screen resolution was set to 1280x768. I opened "Educational sweet Gcompris" and the resolution changed to accommodate the program(800x600 i think), but when I closed the program the resolution didn't change back. I opened "monitor resolution settings" and it said that the screen was still set to the correct resolution. I tried to select it again to force into refreshing the screen but it did nothing. I then changed it to 1920x1080 to get it to another resolution so that I could try to change it back. It went to 1920x1080, but now it is stuck on that resolution. If I try to change it, the screen flickers to the new resolution then right back to 1920x1080 and asks me if I would like to keep the current settings or go back to the old one. In either case it always stays the same(1920x1080). I have tried to use other resolutions but to no success. I even tried to change it through compiz by deleting 1920x1080+0+0 and replacing it with 1280x768+0+0, but that didn't do anything. Does anybody have any solutions?

Ubuntu 8.04
ATI Radeon 9600SE
samsung 56" 1080p hdtv