Andrew:

If in fact the negative quantity on hand was the result of a return to vendor, please don't do anything about it. I can just imaging the irate call now "What do you mean the software will not allow me to post this return of stock! I already returned the items!!".

Kind of like the same reason we don't recommend using this feature in the first place. "What do you mean the software won't let you sell me these items! They here in my hand. I want to buy them!. For which all you can do is try to explain that the computer will not let you sell them as it says you have none in stock.":)

Errors in inventory should be investigated but the fact that the software says you have none when in fact you have them in hand shouldn't prevent you from posting the required transaction.