Car Alarms: Car Alarm, ford mondeo, random intervals

Question
I live in UK and recently bought a used 1998 Ford Mondeo 2.5 V6 - a very clean car with full Ford service history but I have a problem with the inbuilt alarm. If I lock the car thus initiating the alarm immediately after driving, the alarm will sound off in a matter of minutes afterwards. If I park the car and leave it for say, an hour, and then lock it, then the alarm does not malfunction. If I leave the car unlocked then the alarm sometimes, only sometimes, starts emitting an irregular beeping at short spaced random intervals (sounds like morse code)and the lights flash. The car is always driveable when started normally with the key. Even when the irregular beeping is occuring it can be started and driven normally despite the fact that the engine immobiliser light on the dash is flashing erratically and the car lights are flashing and the alarm horn beeping - very embarrasing. Can you help with this problem.

Answer
My guess is a bad ground on the aftermarket car alarm.
The intermittency denotes a abd connection, and in my
experience, it is a bad ground being supplied to the
brain, controlling all points.

Have this checked if possible, and get back to me
with the result. If not the reason, I would remove the
system and reinstall another for safety.

Cheers.

ALARMTEK
CARALARMCITY.com