|Yeah, it sounds mighty like viral activity. It might be a lot less hassle to totally restore the system. Did the computer come with a restore CD or some other feature to enable you to do so?|
If you should go that way, back up your own stuff first. After restore, get a virus checker and use it on the backup media before you put it back on again.
How to know you are getting old 6:
You can't remember what it is that you have forgotten.