Unable to connect to this Team Foundation Server...
Microsoft Visual Studio 2005 pops up a nice dialog with three possible reasons for failure:
The Team Foundation Server name, port number or protocol is incorrect.
The Team Foundation Server is offline.
Password is expired or incorrect.
They should have added: Your machine.config contains an error. In this case a coworker added an appSettings section to the machine.config. He added valid xml; no errors at all. So why blame the config settings you might ask...
Well, apparently the appSettings node must be located below the configSections node. If not, all kind of strange things (like not being able to connect to TFS) will occur.