Did you uninstall Release Management Server and lose access to the Release Management client?
It can happen. If you uninstall the RM server and a client is still pointing to that server (one that is now no longer available, because you just uninstalled it), you will get this error message the next time you launch the client.You can recover by using ReleaseManagementConsoleAdjustConfigFile.exe, a new command line tool included with VS update...