Well, first question is, is it the same thing that you're plugging in and out that causes the problem? If so, then that item itself may be the problem (the wires in its plug/cable/whatever are shorted). If not, then it could be the socket. I had a similar problem and an electrician did say that the sockets "go bad" once in a while. I didn't really believe him though. In any case, there is no harm in replacing the socket. They're only about $15 and easy to do. I wouldn't hire an electrician to do it though.
There's another possibility too. It's possible the breaker on that circuit is bad. I had this problem too. Replaced that breaker, problems with that circuit went away.
