Video Corruption on Xorg w/ATI Mobility Radeon 9000

Hi, I'm having problems with corrupted video on the ATI Mobility Radeon 9000.

My machine is an IBM Thinkpad T40.

The video card has 32 megabytes of video RAM.

Whenever I set the resolution to 1400x1050 (the native resolution of my LCD display), the display becomes somewhat corrupted. The mouse cursor region becomes ~32x32 pixels of random colors (usually lots of white), and the bottom and right edges of the screen have irregularities. Typically, the right edge of the screen shows the content of the left edge of the screen. Any ideas on how to fix this? Thanks.

[599 byte] By [strstrep] at [2007-11-25 22:55:10]