Comment 13 for bug 95880

Thanks for the bug report!

While the symptoms are a little different, this appears to be a dupe of 3731. The root issue is that Ubuntu failed to detect the hsync and vrefresh freqs for your monitor, and since they weren't listed in the xorg conf file, Xorg made some incorrect assumptions about them. With this incomplete information, Xorg sometimes decides to use 1024x768, and other times 800x600.

Notice in your xorg.conf file that the h/v rates aren't listed. A workaround would be to use the rates shown in your xresprobe tests (or look them up in your monitor's documentation) and add them to the monitor section of your xorg.conf file.

A true solution would be to fix whatever misdetected your monitor in the first place; since that's the goal for bug 3731, I'm marking this a dupe of that one. Please let me know if you have more info or think I'm on the wrong track here. :-)