I had a rattle that sounded like a bit of grit in the speaker and the dealer took it all apart and said they found nothing - eventually discovered that it was the trim 'rattling' against the door - if you get someone to press the trim while your driving (or do this yourself in a very large field!) and it stops you can tell the dealer where it is. I think others have reported something similar and the dealer puts pads between trim and body (or is it blue-tac?)

MCC Astro Black, collected 21 July

, all is well (alarm has not false alarmed since 15 December 2004!)