Can OpenERP cancel availability of a Stock Moves if the goods are not available anymore?

During a Stock Inventory, it may happen that the real stock level is lower than the computed one for a product.
Or you could have to deliver a product in emergency, even though it was assigned to another Stock Move.

But even if you enter those facts in OpenERP, it won't cancel the availability of a Stock Moves in any circumstance.
Automating this type of re-scheduling can be very complex and it's not the goal of OpenERP to cover this sort of "accidental" cases.

As for most "exceptional" events in OpenERP, your best move in these situations is to have a user review the Stock Moves that were wrongly assigned.