Maybe your computer crashed? I'm not a technical expert though. And if someone already posted that possibility sorry, I'm too lazy to look through all the pages.
Check to see if all your files are there because normally when a computer crashes it loses a lot of data. It's happened to me many times... haha. But causes for that is a virus. And I don't know what that Windows NT is, but it could be a virus. Not sure. Just trying to help the best that I could. Should definitely get it checked out. Well good luck with that.