I've had someone look at my furnace, there stumped. It's a nordyne furnace, only a few years old, works great except at random times it just shuts off, usually in the middle of the night. It comes back on by just turning the thermostat off and then back on or opening the door on the front of the heater and closing it. Then it works fine until it happens again without warning.

Clean the flame sensor. Report back.