Some hackers were able to insert a spam link into the header of this blog. Two of my readers kindly informed me by mail of that fact.
I have installed a new version of the latest WordPress software from scratch. I hope this solves this problem. If not, it may at least help to find out what is happening.
It will take some time to get everything up back running. But as long as the spam links are gone, I will switch off maintenance mode and make the blog accessible, even if there are still some things missing.