Coil goes bad as soon as I turn the key in the ignition.

My ignition coil in my 1993 Toyota Camry went out, so I replaced it. About 4 months later it went out again, so once again I replaced it, only this time as soon as I turned the key there was nothing, so I checked the spark and there was none. After some checking I found that the primary coil resistance once again measured wrong so I took the coil back to the auto parts store and they replaced it. This time we checked the resistance while I was there and the coil was good. I got home put it in the car and again turned the key and the engine turned over but wouldn't start. Once again the primary resistance was bad. I then changed the igniter, ignition switch, and distributor and once again as soon as I turn the key the primary coil goes to 0 ohms resistance. The plugs and wires were changed when the first coil was put in the car, I am now at a loss as to what to check next, any help would be greatly appreciated.