Please help - Alam goes off Intermittent freelander TD4 2004

Hi could anyone please help me, I have a Freelander TD4 2004 SE
The Alam has started to go off intermittently, I've had a good look around
hooverd everywhere in side the car in case of spiders (dont no if a small thing like that would set it off anyway), closed all air vents off.
the alam goes off maybe once or twice a week then it will be fine for a couple of weeks, then starts going off for no reason again... at all times day and night.. much to my neighbors moans... the car is kept on my drive away from the road and anyone passing, cant afford to take it to a garage for an electrical check, im pritty handy on the mech side of things.
so any help advise would be most welcome
ALSO DOES ANYONE KNOW HOW I CAN LOCK THE CAR WITHOUT THE ALARM BEING SET.....

I'd re-post this into the Freelander section.
Sorry I can't help, I'm a Rangie driver and if you think you've got electrical issues!!!

If the alarm siren has battery backup on it the internal batteries fail and cause these symptoms-lot's of vauxhaul suffer this.