SL won't let me switch to 1920x1200 res

I just picked up a Dell 2405FPW 24" monitor today, however I cannot get Second Life to switch to 1920x1200 full-screen resolution.

After I try to switch it, the screen blinks black a few times, then SL returns with a message stating "Failed to switch resolution to 1920 by 1200". The highest full-screen resolution I can choose from the Preferences pull-down that works is 1360x1024. I tried manually editing the settings.ini to plug in the full-screen resolution, however when i try to run SL, it still kicks back an error message and defaults to windowed mode.

Other games play fine in 1920x1200 full-screen, however SL isn't being agreeable. Here are the core specs of my system:

AMD Athlon64-3500 w/ WindowsXP Pro @ SP2
ATi x800 w/ Catalyst 6.1
Dell 2405FPW w/ 9.1058 drivers

Anyone help in this matter would be appreciative, thanks!

Have you tried messing with your aspect ratio in game, not sure if that will do anything but its worth a try. Your screen has a 16:10 ratio, a normal monitor has a 4:3 so this may be your issue.