BMW 330i 2003 model... Recently, the alarm has been going off sporadically... doesn't always happen and doesn't happen at night.... Any ideas? Alternately, how can I disarm the system until I get it fixed

I would recommend checking the hood switch. Raise the hood and lock on the left or right strut tower area. You should see a small switch with a rod that sticks up.try disconnecting the switch and see if the problem goes away.If not you have an interior sensor on the headliner under a trim cover. The cover is clipped on.pull the cover down and try disconnecting the sensor to see if it fixes it.

BMW 320d sport touring 2003 alarm goes of intermitatley/ hazards don't work some times when setting the alarm with remote
If you open and close the bonnet alarm sets but after a while the alarm goes off again.

Fault traced to bonnet switch found just in front of brake fluid reservoir. switch bracket broken. Remove switch from bracket
Supper glue bracket and clean switch with electrolube switch cleaner. it worked for me. Hope this is of help. Neil