The problem you are reporting is probably the same as some other users with special
characters in the user name have reported.You are in luck the next version is about to be released this week and a fix for this problem will hopefully be in it.
If you want more information I suggest you search on "cookies delete" in this forum.
They will show within the last 45 days at the most.
Good thing you provided the info that you are a user in Germany.