Doesn't seem limited to GE Microwaves! My wife uses a cheap Kmart house-brand microwave for waxwork that does the exact same thing.
I have another in the kitchen (Panasonic NNCD997) that has an interlock system which blows the primary fuse if a) The door is open and b) The magnetron is currently active.
Unfortunately, with this model, the incandescent bulb dying kills the inverter PCB.
Edit: The service/repair manual[1] for the Panasonic is an interesting read, if anyone is interested
I have another in the kitchen (Panasonic NNCD997) that has an interlock system which blows the primary fuse if a) The door is open and b) The magnetron is currently active.
Unfortunately, with this model, the incandescent bulb dying kills the inverter PCB.
Edit: The service/repair manual[1] for the Panasonic is an interesting read, if anyone is interested
[1] http://up.orificeworks.com/nn-cd997s_cd987w.pdf