what's your technical knowledge like?
if you can't even do anything in safe mode then you're probably not going to be able to run the standard virus scanning stuff, so pretty much the only way to figure out what's going on is to use tools like process monitor, which you can get here.
you might be better off just connecting the boot hard drive that you're using to another computer, copy the files off it that you need (i.e. stuff that isn't the OS install), connect it back as the boot drive on your main computer then just run a format to reinstall windows from scratch, then copy your backed up stuff back over...