Craft queues can be corrupted when changing ME scheme (adding/removing interfaces, cables etc).
Craft queues partially corrupts in parallel crafting. Ex: crafting Transformer Upgrade (Industrialcraft2) needs to craft Insulated Gold Cable, MV-Transformer and Electronic Circuit, that at last needs Rubber: the Rubber crafted partially, beause crafted in parallel for Insulated Gold Cable, Copper Cable for MV-Transformer and Copper Cable for Electronic Circuit.