Thanks for the information! I will start trying all these options right away and if I'm unsuccesful in solving this problem, I'll post all the information you requested.
BTW. I'm playing with the CD in my drive, so no no-cd crack. I'm a bit afraid that I won't be able to fix this because the character was created with the retail version and I patched afterwards. In the patch readme I read that some of the story fixes require a new game to be started.
