mouse problem

Hello I have a problem with my laptop and SuSE 9.0. When I start up kde the mouse pad on the laptop works fine. When I connect a external mouse (PS2) on the running system also everything is fine. The problem is if the external mouse stays connected during a boot/startup the laptop mouse pad and the external mouse don't work anymore. All adjustments I tried in yast failed. Has anybody an idea what can cause this problem? Regards Stefan