crippled gnome by trying xgl/compiz

[Marco]

Hello,

I created a session profile to start xgl. Finally I could start gnome by
reducing my xorg.conf to single monitor.

Then in gnome console I entered:
$ gnome-window-decorator
$ compiz --replace gconf
compiz.real: No composite extension

Now I have the problem that all windows are missing the window-decorators
and basic keyboard shortcuts are not working anymore. I can't move windows,
switch windows, and also the taskbar is gone.

Gnome is even crippled if I reboot and start a normal gnome session.

How can I repair my system?

Please help!

Regards,
Marco