We have been consolidating our Hyper-V system of late, moving various older systems onto a new SAN based cluster. This has meant we have just moved our virtual TFS2008 build machines. After the move I started seeing the following error on all the builds using that server, re-enabling the build machine had no effect.
I restarted the build VM but this did not fix the problem; I had to also restart the TFS2008 AT, once this was done all was fine. I guess that there was a cached IP/ARP table somewhere routing packets the wrong way.
Technical Tip: if you can’t see the build server don’t just assume it is always the build server at fault, it might be the other calling machine i.e. the TFS AT
Interestingly our TFS2010 build machines did not suffer this problem.