hobotroid

Hi, sorry if this is the wrong place to post this.

I'm using the Standard Big World install of BG1+BG2+expansions, and I'm on the final battle vs Irenicus in hell. The strangest thing happens when the fight begins...

I cast a firestorm and stinking cloud on the spot where he's going to appear. He does so, then we do the dialogue, and he summons the 4 demons and the fight begins. The aoe spells have done some damage to him at this point, and he just runs backwards (north) into the black door and disappears completely!

I then fight and kill the summoned demons, and he *never* comes back. I have no clue what's happening. I can't save or rest at this point (monsters are near), and I can't exit. I'm stuck, and he never comes back.

I'm wondering if this is caused by a glitch in one of the Standard install mods that come with Big World? If anyone can give me any tips (perhaps how to remove any mods that may affect Irenicus?) I'd be greatly appreciative.

Thanks!

ps - Could this be because of my aoe spells I cast beforehand? I've tried the encounter without them, but Irenicus timestops *twice* and kills my entire party before I can do anything. That's an issue with my naive gameplay style though, not a bug. Though, I get the impression that he is this difficult because of a mod? Can I get rid of that mod somehow?