External monitor

I’ve connected an external monitor to my notebook. Everything worked fine in openSUSE 10.3. Everything was presented on the internal and external monitor. I had only to switch on the external one manually after the boot when the X server has started. Now with openSUSE 11.0 only the output of the boot process and the init 3 level shows on the external monitor. As soon as the X server starts there is no support of the external monitor at all. I’ve already tried several drivers as ati, r128, radeon etc. Nothing helped. But when I restalled 10.3 everything was fine again. I checked the xorg.configs of those two versions. Concerning the settings of the device, screen and monitor settings no differences. Only the drivers have different version numbers. It was in both cases the ati driver.
The chip set of my notebook is “Rage 128 Mobility M4 MF”.

Has someone an idea what could help?