This forum thread explains this, http://www.bay12forums.com/smf/index.php?topic=144100.0

A doctor and a patient are locked into a diagnosis loop. The patient has a broken arm and an infection, and is in a traction bench. He has pages and pages of "evaluated" in his treatment history, and the docs just evaluate him endlessly at this point.

The game was originally started in 40.10 I think it was, and is now running in the 40.13 version.