Hi Christof,

While you *might* have a software problem, slowdowns are reasonably
typical when hard drives are physically faulty. Potentially, you might
have lost some data, too. Someone else on this list might be able to
recommend your steps from this point forward. If you don't have backups,
I'd suggest that you get someone professional tell you what to do next.
I could imagine that trying to back up your hard drive now may make
things worse, depending on the nature of the damage (if any).