How do I stop my alarm going off every time i lock my Lexus IS200?

Right I had the same problem & took the following steps which worked for a short while but it is happening again

Firstly, if your battery voltage drops it will set off your alarm so chaqnge that if you have prob lems starting your car
Secondly, the air vents might need closing which might solve this
Thirdly, clean all of your door & boot & bonnet contacts
Lastly, know of anything as I have done all of the above but have had no luck as it was fine for a month now is doing the same thing on a random infrequent basis

Asif Shah
June 2008