Locked the keys inside!

[lockout]

My 96 VR6 has taken to locking itself, about 1 minute after exiting the car and closing the door - when the immobiliser cuts in the doors lock too, even if the keys are in the ignition (Yea tried that one!) Its a recent thing, had the car from near new and it only started doing it a couple of months ago, following a flat battery. Coincidence? Anybody got any ideas please? How can I recode back to original spec? Anybody got full instructions for these units? Full sequence of events is Turn off engine, remove key, radio goes off, yellow warning light flashes 3 times rapidly and repeats, exit car, close door, red light flashes slowly, after 1 minute doors lock and windows close if open (as they should of course!) Everything else seems to be ok, interior light etc. PLEASE can anybody help before I strand myself somewhere I don't need to be?
Thanks!