The suggested tip does not work. I don't have more info on the subject. Could you be more specific in what kind of info you need? I do want to solve this issue

I did that. It erased my career in that specific player profile/nickname. I tested if the same thing should appear again, but it didn't. I am now in Camp Maxwell.

Case closed.

Thank you guys for your help!

Thanx for the quick reply. I did what you suggested. Steam validated the whole bunch of local files, all successful. I retried reverting the campaign, but the same thing happened. So it didn't quite work out :/
Other ideas? An entire new install may do it? But will I lose my savegames if I do that?