Peter, Tony: I am a bit of a geek, on the QT, you know, and I had Microshite's anti spyware updated automatically, as was AVG. I'd defragged the hard drive recently. In fact, I'd done everything a good geek should to keep a PC running smoothly.
What actually happened was, I spent a few hours on Saturday morning surfing, and then I'd turned off the computer fully... Later, I switched it back on and got that chilling message inviting me to boot up in safe mode. BUT it wouldn't even let me do that, I restarted several times with the same result: I couldn't actually get into Windows so there was no way I could get on line and get help.
So, I reloaded Windows from the CD (short of a full reformat), and it booted up but it was very slow: and dialogue boxes kept popping up: one was telling me .net framework couldn't run, and another was wanting to install HP photogallery, for God's sake. No matter how many times I clicked on them they'd come back. It was really slow, but I managed to do a virus scan: nada. Nothing else would work, I tried to install the programs it was after, but couldn't. After several hours, dozens of restarts, and much use of the 'c' word, I gave up and reformatted the hard drive, naturally losing all my data because it wouldn't read the blank CD I was trying to burn it to.
Now, obviously, it's running again. But it's really slow, and I'm going to be most of today nursing it back to health.