Thanks for help so far.
This time i attached the files :-)
I attached the XFree86.0.log and the "tail" of the messages-log.
Both are from today right after booting.
When booting the system tries to load kdm and the gui-login. But this does not work.....the screen is black. Then i use Ctrl+Alt+F1 to login as root.
Then i copy both the XFree86.0.log and the tail of messages. So they are from the same session (see the same date)
Thanks for analysing my logs :-)