I've had several server crashes lately that I've isolated to the following scenario:
A ComputerCraft computer connected to an AE2 interface requests autocrafting via the OpenPeripheral-provided API. Before crafting is complete, the chunk containing the computer is unloaded. When the autocrafting is complete, or is cancelled for any reason, the crafting processor attempts to notify the requesting computer of the crafting result, but as it's not there, an exception ("You are not connected to this computer") is raised and the server aborts.