I was doing some testing today of a Windows Phone 7 application. Specifically, I disconnected my computer from the network to test the piece of code that checks to see if the phone has network connectivity. This puts Team Foundation Server into off line mode.
After doing some internet research, I then went back into my Windows Phone 7 project and tried to edit it. It wouldn’t allow me to edit the file and would move to the beginning of the current line when I pressed the enter key. The reason for this is that even though I had finished testing and reconnected my network connection, TFS was still in offline mode.
To be able to edit files that are checked in, it is necessary to click the reconnect icon to reconnect TFS. This fixed my problem.