Is this for real? I hired a new admin person, who wasn't sure how to accept an advance deposit - so she created an item invoice to apply it to. Some of the items were incorrect, but since one was a negative inventory item, I can't change anything! Surely there has to be a way to correct this - if not, this is as bad an example of programming incompetence as I've seen.

And another thing! I'm trying to turn off the "Allow the Sale of Items with Insufficient..." preference - but it won't let me, despite the fact that I have ABSOLUTELY no items with negative quantity or negative inventory value. Why introduce this 'feature' if it's broken? Time to find another accounting program...

First, please make a backup copy of your company file.
If all of your inventoried items appear to have a positive on-hand quantity, there are no open invoices or purchases with these items, and you cannot deselect the preference, this might be because although your items all have a positive amount, the value of an item might have been adjusted. Using an average cost inventory method, each item must have a value that is created by multiplying the on-hand quantities by the unit cost to get the total value of the item. In order to deselect this preference after using this feature, you must delete the sale that caused the item to go into negative value. If a sale that caused the item to have a negative value cannot be deleted, it may be because the value of the item currently is different from the time of the sale. If so, delete any inventory adjustment for that item. Please be sure to make a copy of your company file BEFORE you attempt these procedures.
If you are still having difficulties, please contact our Technical Support team at 1-800-662-3788.