topsoftbe on "strange records in wp_options"

Thanks for your reply. I am rather sure it's not the theme, iTheme2. After an update it decently cleans up everything. But I agree about the plugins. I installed two media category plugins and removed them again because they were completely useless, but I suspect one of them to be the culprit.
Anyway, I will keep a copy of the bad blogs, reinstall everything and when all is OK again, I will try to find out what was really happening.
I'll start a new topic when I find out something.