i810: Wrong resolutions on external monitor

[Markus]

Hello,

I have a Sony Vaio T1XP subnotebook, with X.org 6.9.0 (SUSE 10.1) using the 
i810 driver. The native notebook display resolution is 1280x768.

On the notebook itself, the wideescreen resolution now works well out of the 
box, however I am experiencing some issues when connecting an external 
monitor:
Using the 1280x768 resolution, my external screen is run at 1024x768. In 
addition, black borders are added inside the "active" screen space on the 
left and right, thus showing an image which is squashed horizontally (once 
because of the wrong resolution and even further because of the black bars).
Switching to 1024x768 with RandR, the external screen is set to 1280x768. I am 
then getting a stretched picture.
The only resolution that is consistent and undistorted on both screens is 
800x600.

The relevant settings in xorg.conf are:
Option       "MonitorLayout" "CRT,LFP"
Option       "Clone" "Yes"

How can I fix this?

Thanks,
Markus