When we exposed our TFS installation one of the things we noticed was that the Documents and Reports folder in Team Explorer weren't accessible inside in Visual Studio. The problem is quite simple, when the TFS is installed it registers himself with the machine name, but this cut the mustard since when accessing TFS over the internet who are using a fully qualified name and not the machine name that is only accessible in your internal network. (if you see the Documents and Reports folder properties, you will notice that it contains the machine name).
I've been trying to write a post explaining how this can be solved and steps that have to be taken, but other things got in the way. The solution is simple, all you have to do is change the registration settings for TFS so it exposed to it's clients the reporting services and WSS URLs that include the FQDN.
Now i won't have the chance to explain you all the necessary steps, since Martin Hinshelwood not only recently wrote about it, but did it better than i ever would. :-)
He focused on a common error (TF30177) that happens while accessing the server internally, but his steps can also be applied to machines accessible over the internet.
Just a small tip, Martin forgot to say that while editing the XML file you should enclosed the RegistrationEntry node(s) with a RegistrationEntries element.