The problem: the MS Test framework, QTTask.exe, sgen.exe and a bunch of others were throwing AccessViolationExceptions in all sorts of places, but most painfully during my CI build. This mean that our build server couldn't run our unit tests, which meant that TFS Deployer wouldn't deploy because it thought the build was bad.

A red herring presented itself in the form of SQL Server Management Studio also falling in a heap, which led us to believe that it was an issue with the server image.

After wasting an entire day re-provisioning VMs from images, the simple solution was to turn off Symantec's endpoint protection.