Well someone FINALLY came onto IRC to help debug this. No one who's posted here, of course. Thanks for the help, guys. This is why it never gets anything fixed. Hell, maybe I should just
link to the webchat to get the point across.
Anyway. I spent a couple
hours on it but couldn't find the source of the problem itself, because
it's not Caster. I can remove everything Caster does except for the most basic, trivial of debugging hooks, and MBAC still explodes. That means that running the program in a debugger
period causes this problem. So, as I suspected, something in the system itself is getting in the way of Caster working. But I still don't have a clue what, and I don't have a clue how to fix this problem at this time. Perhaps someone feels like braving the horrors of OllyDbg and seeing what they can turn up through it.
I'll do more research some other time, it's getting much too late now...
Edit:
Idea came to me late at night. Try this build. This is completely untested, it might blow up, you're warned. Didn't work, never mind.