PIC chip resetting. Very weird

Hi. Im setting up for the greatest time of year (Halloween). Ive got a switch attached to the front door that connects to a PIC chip. Im using cat5e network cable (twisted pair). The wire passes a smoke machine and everytime the smoke machine turns on/off or fires smoke out the PIC chip resets itself.

So far i have tried moving the circuit accross the room. This doesnt help. If i disconnect the switch at the PIC end then it still affects it within 4 meters but not at the other end of the room. Ive tried running the circuit from a battery incase there was interference from the mains.

If i put the smoke machine button near the PIC and press it then it has *no* affect unless the switch is connected or the PIC is near the smoke machine.

I cant see that there is a supply fault to the circuit. Just having one of the switch wires connected is also enough to make it reset.

Im sure this is because of interference somehow flying through the air into the wire but is there a way to stop it? I cant move the wire far enough away without ruining the whole effect.

Oh yeah. I checked the whole circuit and there are absolutely no shorts anywhere.

If anyone has any ideas can you let me know ASAP please.