boot and shutdown problems

[Johannes Griese]

Hi,

first i upgraded from 11.04 to 11.10 but i had a lot of problems so i made a 
fresh install (without cleaning the /home partition, because i don't want to 
delete all configs).
Everything seems to work quiet well exept booting and shut down.
When the kernel booted and actually kdm has to start there is only a black 
screen.
I have to switch to a virtual console (strg + alt + f1, no log in) and back to 
xserver (strg + alt + f7) so that kdm starts.
The same happens while shutting down, so i see a black screen, nothing 
happens. But when switch to a console the computer continues the shutdown.

It would be great if someone could help :)

Sorry if my english is hard to understand but i am not a native speaker.

greetings