A strange thing has happened to my website

My website has been playing up for a couple of weeks now in different ways, but yesterday it became most alarming. It looks like my site has been taken over by Microsoft IIS7. Also, from being the first few results for a number of years, I am suddenly almost impossible to find on google.

Does anyone have any ideas as to what could have happened and what I can do about it?

It feels a bit like I'm in an alien B-movie...

If I don't blog for a while, it's because they've got me.