I set my screen to 1200x1024 the other night without any problems.  When I went to start the client tonight the screen was badly askew; horizontal and vertical size were off, position was off, generally a mess.  When I set the resolution back to 1024x768 it worked just fine.  After playing a while I was able to set the resolution back to 1200x1024 and the default horiz/vert was fine.  Almost looked like the refresh rate was changed in the client somehow.
I normally run 12000x1024x75Hz.
Any ideas?  It's an annoyance more than anything, but I'm curious how the client handles the refresh rates.
GeForce 3 Ti200
AMD XP1900+
Soyo K7V Dragon+
256MB PC2100 Ram