Ok, after I turned off any power management options, the error disappeared. Thanks for that so far…

But when I try to boot up, I still get the "Restart your computer"-error, I also reported that on my first post.

So I tried to boot up with displaying diagnostic messages ("-v"). But everytime the boot process stops at a different point. The log doesn't go on, and I cannot hear any noise from my HD (which is usually that loud, that I can hear it working)

I also tried to repair the partition permissions etc., using the dvd. Any help?