I've had an issue lately that has kicked me around...that is, until tonight :).  I have TFS 2008 set up on a remote server that I connect to via a dedicated VPN tunnel.  This particular server participates in a Windows Server 2003 domain but my workstation is not a member of the domain.  That said, my primary development environment is a Virtual PC machine that is on the domain.  Therefore, the credentials that I use on my VPC are domain credentials whereas the credentials that I use to sign on to my workstation are local credentials - they do not match.

Back when I initially set up TFS connectivity was a snap.  Visual Studio (actually the Team Explorer 2008) on my VPC (being on the domain as though it were local) simply connects to the TFS server and I can work with the data easily.  I wanted, however, to connect to the same TFS server from my workstation.  This proved to be more of a battle than I had expected.

Almost invariably, upon attempting to connect to the server in the Team Explorer I would get the seemingly infamous "TF31002: Unable to connect to this Team Foundation Server".  What was most perplexing was that I did actually connect a couple of times but when I restarted Visual Studio (or even after just a few seconds) my connection was lost.  I could ping the server and I could access the web service (http://servername:port/services/v1.0/serverstatus.asmx) just fine, but I could not connect in Visual Studio.

I spent hours trying every trick I could think of to no avail.  I could not get it to prompt me for credentials (even though I had selected that option in Internet Explorer's Intranet security settings) and my network credentials established for the TFS server didn't seem to have any effect when accessing it through Visual Studio.  I won't go into any more details about how I troubleshot the problem, but suffice it to say, NOTHING I did seemed to affect the outcome at all.

In my research into the problem I saw that a few people had resolved this issue by uninstalling their McAfee AV software.  I don't use McAfee, but I do have AVG 8.0 installed.  This proved to be the tipping point to solving the problem.  I had disabled some AV settings when I was first attempting to fix the issue, but it didn't seem to have any effect so I wrote it off.  Well, it turns out I was just turning the wrong knobs.

The solution that worked for me was this:

1. Set up a network password (Control Panel - User Accounts) for the remote server using my domain credentials.
2. Open the AVG User Interface -> Tools -> Advanced settings.
   1. Expand the Web Shield option and select Web Protection.
   2. Uncheck the 'Enable Web protection' option.

After that, everything was smooth as glass. :)