Minecraft – Inventory opening and closing

I know you checked your shift key, but 1 explanation would be that you pressed shift multiple times resulting in an affect called sticky keys. One way to remove it is press shift repeatedly until your computer has a pop up message. Then you have to press cancel or something.

Sorry if this isn't specific enough.

If you attach a logistic chassis with an extractor module (either mark 1 or 2) to the side of the furnace it will extract any excess products from the furnace and send them to the default route, do not worry about the extractor module taking items that the crafting pipe was waiting for as it has a lower priority so will not take the items unless no other pipe wants it.