Yeah thats exactly what it was, I was testing the Julii and the game was obviously looking for Segesta in the various scripts. I'd originally replaced any reference to Segesta with Genova, so I figured that was probably the cause.

Thought the CTDs might have been caused by other factors, namely the spawning of SPQR family members around Rome (IE spawning onto the river). However, the game is pretty smart and spawns them onto fords instead, good stuff and saves more debugging