Shut down the box and check the connections. Bet you something isn't plugged in all the way and the system didn't see the hardware properly when it booted. I see it all the time.
At my home I have hardware available for people who are guests. That way they're not messing with my hardware that is actually used. Typically, guests get an old LCD or CRT monitor, an old keyboard and an old mouse to use. They work fine and it keeps of course, things from breaking that shouldn't ever break by having people pull hardware from my own systems. The hardware we actually use is under lock and key. This includes all of my networking gear, the electrical panel, a few computer towers in heavily trafficed areas (They are getting plenty of ventilation, so they're not in a standard desk shelf), and my gaming PC which I built myself (room is always locked as it's also where I keep my other personal systems and work on other systems from people who need help). Also, the Administrator accounts on every PC, whether it's a Linux box or a Windows box, is under two-part authentication. I've had issues with friends coming over and causing PCs to grind to a halt for setting the system clock back to 1980 or 1960, and this was way before the days of me having the knowledge or ability to set up Group Policy and Restrictions on machines (years ago).
Also, I know the feeling. There are some people who despite my best efforts to tell them that the problem they keep telling me about is the same thing but in a different (slightly) form, continue to tell me about the same problems. Then there are those who I do things for them, then they undo what I did, ask me why something broke and I have to fix it again. Then of course there are those "It should just work" type of folks who give up if something doesn't work the second they try to use it. These folks I tell to Google-It or Bing-It since it's often something I can fix right away and have given them the solution to already. Being a computer technician is fun, and I do enjoy it though!
