Damn. I wonder why these problems didn't occur in the playtesting-time.
I did turn of the dialog options when you got the specific item, but it seems that the dialogs options won't be turned on again, when you lose the item.
Well, I added some lines to check wether you have the item or you don't, so if you don't have it, the options will be turned on. I didn't think that this is necessary.