Shot in the dark...
We are running TC3.1 build 6760 with 4 build agents. We had a problem this morning where our tagged UAT build tagged the latest code, but used an old version of one of the config files. It was fixed by clicking the clean sources button for the agent. But we have clean before build selected for the build.
I don't suppose this is a problem that was fixed in 3.1.1 ?