Unexplained Jenkins errors

I have a Jenkins project that runs a little over 30 tests through MTM. They're selenium tests and take a bit over 20 minutes to run. 6 of these tests are new (2 tests, 3 iterations each) to the project, and error out for the same reason every time they run.

Here's the catch: 1. They pass locally 2. They pass when run directly through MTM 3. They pass when run through an identical Jenkins project without the other 25ish tests.

I reboot the test agent VM at the beginning of both Jenkins jobs. The specific error is from Castle ActiveRecord telling me to initialize a class I have most definitely initialized in the code.