Rover 414 95 - randon alarm problems & immobiliser?

HELP !!! - I have a rover 1995 where the alarm is inhibiting the ignition and sounds the horn with what appears to be random blips,, ive tried resetting the alarm by removing the battery - ive tried reseting the alarm with the code I have (following the manual) - no joy.

Ive tried various conditions with the interior light and the doors getting locked etc..

Could someone shed some light on how i can get the alarm stable - or better still - DISABLED ?