So I am stuck at this point where you have to talk to Mother Superior. 
Everytime I come close to the point where the mission starts my game crashes. First I thought my PS3 is screwed up but it only crashes at this point, not if I ride somewhere else. 
 
Did anyone else experience this? 

From what I've seen, which is about 2 hours at my friends house, Undead Nightmare is really buggy.  
Doesn't stop it from being awesome though.

It happens pretty often to me too. Specifically at that point you mentioned with Mother Superior aswell. No way to get around it besides just trying again and having hope. Maybe even pray, considering the place of the game crash :P

That's weird.  It never happened to me.

My game hasn't crashed, but I'm pretty annoyed by the fact that a group of like 20 zombies will just spawn right in front of me, out of nowhere. That's pretty lame.

Okay a friend told me how to solve this problem, you just have to log out of the PSN and then the game won´t crash lol

no bugs here