[old_master]

There's a switch in the hatch lock cylinder, like you mentioned, that locks/unlocks the doors. I suppose there's a possibility the wiring or switch is shorting out causing the locks to go haywire. If/when you stop by the dealer, ask the service advisor to check your RPO codes and see if the vehicle is equipped with keyless entry. If not, have him/her take a look under the dash for an aftermarket, (add on) system. That would be a far more likely reason for the locks to malfunction.