I logged in today with Iri and checked the bank chest, right beside where I logged out. Instead of an inventory, I got the message "You are already using a bank chest" in bright red letters. So I tried resting, making a deposit with the vault keeper, using the crafting benches, and logging out and in again, but it doesn't help. I don't remember logging out with the bank chest open last night, but I may have, and I can imagine NWN being picky about that sort of thing.
I'm out of ideas, so if anyone else can help get this fixed I would appreciate it. Thanks.