I've been able to recreate and isolate the cause of the wu jen's inventory bug -- it has to do with the Enchanted Blade spell. Brian did some work with that spell to prevent an exploit, and it ended up resulting in a bad jump pointer to some scrambled bits of code. The funny thing is, sometimes it works fine, and other times it causes the inventory issue. Anyway, I'm probably going to try to revert Enchanted Blade back to its original state in v1.2, even if there is a potential for an exploit. The spell in v 1.2 was definitely one of my favorites. What's not to like about creating a magical sword that shoots lightning bolts on command?
So Olivier, you should be fine if you just avoid using the Enchanted Blade spell when playing TD2, or you could try it and just go back to a previous save if it acts up.