As was to be expected, my ISP says they didn't do anything, so it's my fault, of course. So I reconverted my home page to good old HTML and deleted my Serendipity blog system.

Thank you so much for your helpful replies. I will first turn to my ISP and see what they can do for me (nice lyric, isn't it?). But you will "hear" from me here again.

Today I discovered that my blog suddenly looks totally different (new template) although I didn't change anything. What's worse: When I try to log in, I get this message: You can no longer login with an old-style MD5 hash to prevent MD5-Hostage abuse. Please ask the Administrator to set you a new pa...