This depends - are you loading a previously saved game, or is it a fresh game?

If you're loading one, my guess is that you simply have an item in your inventory that you deleted later on. It's also possible that you have an item in there that you changed to, say, a weapon later on.

If you're doing it fresh, and you have NO items in your inventory (make SURE of this, don't add a single item anywhere) then I'm going to have to try and duplicate that error somehow and tell you the results.