Thanks for getting back to me guys.
Dave,OpenGL was on but turning it off didn’t fix the problem.
Kevin, multiprocessing was already off.
Oddly, it seems to be a corrupt comp. I started a new comp and then pasted the layers one by one into it to try to isolate a bad layer.
As it turned out, I pasted all the layers from the old comp to the new
and it works fine now. The old comp still hangs but the new one works
normally. I didn’t know you could get a bad comp but there you go.