I'm in the Cathedral level 4 and everytime I try and start a new game it crashes. Anyone know why?

Sounds like a corrupted save. Do you have any others?

Save often, and make as many as you can is the best advice for playing the orginals.

I had a similar problem where I couldn't go upstairs or it would crash sadly I don't think there is a fix but let it be a lesson to save in multiple slots.