Just to put some more ideas into the mix - have you tried changing the fullscreen/window options? For example there are options for GameEx to switch resolution, not switch resolution, run in fullscreen with no switch, run in fullscreen with switch, run in fullscreen window etc etc. I agree with u-man, the resloutions you are forced to don't seem to be the norm anyway, AND you're trying to create a vert theme too. You could try making a quick copy of your theme and natively make it to your required resolution, just to see if it remedies anything, then you might get an idea if it really is your hardware playing up or something is happening during the rotation. Either way in my experience a lot themes glitch-out if not displayed at their created resolutions even if it's in the same aspect ratio. Then again only some do and others are fine