I believe I have found the issue, after spending a lot of time messing around with the game. The fault appears to be at the point after defeating Undead Sassan where Sassan asks if you want her to summon the Demon. Every time that I used Mindread on her at that point, without fail, the game would stop functioning after Razakel runs away. If I do not use Mindread on her at that point, the game resumes as it should.
Onward I go...
