Just to recap a little, Paul, can you get into Safe Mode, by continuously tapping the F8 key while your PC is starting?
If so, are you saying that you still cannot start any of your programs, even in Safe Mode?
It definitely sounds like you have been infected with a virus, and possibly more than one, but if you can get into Safe Mode, you should[/i] be able to launch your anti virus software from your desktop, and run a complete system scan. Before you go into Safe Mode, assuming you have XP, you should disable System Restore by the method in the link in my earlier post.
1. Right-click My Computer (on your desktop), and then click Properties.
2. Click the System Restore tab.
3. Tick the "Turn off System Restore" tick box.
The only difficulty with the above is that your anti-virus protection may not be up to date, and as you can't launch it while you are online, that would be a bit tricky, but it should still find something, which might help a little, then we can progress from there.