This may seem like a no-brainer to some, but I beat my head against the wall for a while with it.  If you are trying to get the latest version from Team Foundation Server for a project, and you get an error stating that the Server has committed a protocol violation, it may be due to Windows Live Family Safety if you have it installed.  As soon as I turned Windows Live Family Safety off, I could get latest version with no errors.  I actually just decided to completely uninstall it.  I just wanted to try it out to see how it would work for my kids.  Moral of the story—Windows Live Family Safety is probably not a good idea on a development machine.