remote central locking

[paleface]

Hi out there. I have just bought my first Volvo and this is my first post on this forum. The car is a 1995 440 and there seems to be a small problem with the interior light affecting the remote central locking. When the light switch is in the door open/on position and the doors are closed but not locked, after a couple of minutes the doors lock themselves and a few seconds later the side lights start flashing and do not stop. Any thoughts would be appreciated. It is not urgent as does not affect use of car but natural curiosity says I have to investigate it.