I set the max inventory size to 2147483547 and it crashed when i loaded the world.
Crash report: http://pastebin.com/i2yejFN0
It also happened when i set it to 2 billion.
Mod Version 1.0.4

Well that's what happens when you run out of Java memory, not something I can fix either. (No one could ever use 2 billion slots anyway)