There is a site:
www.annoyances.org that is very good and could help you. It is a forum and all you need to do is to post you problem and they will help you. I have used it a number of time with some problems that I have had with my computer and they have helped me every time.
Yes you should check out what he is doing. I went through the teenage years with three of them and now I am going into it again with two more.
I have a strict policy of no passwords for anythings and if they register on any site, they have to use one of my emails, that way, I know where they have been. I also check the history at least once a week, to see where they might have been. I also "explore" my harddrive once in while to see what they might have put in the computer. They don't hide anything, but my computer is in the same room that I stamp in, so they don't have much of an opportunity to do something that they shouldn't.
DEB