electrics immobiliser-related peugeot 306?

I have had various problems, headlamps, alternator, headlamps, etc. recently, finally fixed by another autoelectrician who removed the dim-dip facility (didn't even know it had one!). However, the headlamps now flash abour 20 times whenever I unlock or shut down the car. The headlamps now seem to be related to the immobiliser circuit , but everything else is OK (oh - except sunroof but that's probably just given up!).
Any ideas?