When I try to connect to a TFS from Team Explorer I get the "Unable to connect to this Team Foundation server... Operation has timed out" error message. From the same machine, I can browse to the TFS website (http://ipofTFSmachine:8080/tfs/web) from Chrome or IE with no problems. From a different (also remote) machine, Visual Studio can connect to TFS no problem. I'm having the problem on just one particular installation of VS.
It just started happening when I renewed my MSDN subscription and entered the new product key, if that makes any difference.