Do you remember when the last time was that you used the Help and Support? Obviously any changes since then are suspect...

Run MSCONFIG, check services and see if any are unchecked for what ever reason. I realize that you have probably already run a virus scan but if not please do so. Also check for Spyware...I've seen a lot of strange things occur because of the unwanted crap that gets left on our systems.
Also what make and model is the computer?
After that let me know.