Hmm - that sounds extreme... Does it still mine when this happens?
I know that --exit-on-zero has some problems and does not close the miner always when it should, but anyways it can close the program gracefully only as long as the system itself is still responding. If even the task manager can not do it I am certain that there is no way for the program to exit any way. Searching for an idea why this extreme stuff hapens.