Car Alarms: Alarm going off for no reason, subaru outback, outback wagon

Question
We have a 2003 Subaru Outback Wagon.  When we bought the car new we bought the Factory Subaru alarm.  For the last week the car alarm has been going off in the middle of the night and in the early morning for no reason.  I brought it to Subaru, and they could not find anything wrong.  It has been raining alot lately, so I am not sure if the moisture has anything to do with it.  Let me know if you heard of this problem before and what the solution might be.

Thanks,

Answer
Sorry, my expertise is in aftermarket
security applications. If this is the OEM
alarm from Subaru, they will need to swap out modules
to determine if it's a "brain" issue, or just
what.

One thing though. Most "FACTORY" alarms, bought at the
end of sale point in that little office, are in
actuality aftermarket alarms. Tell me a little
about what happens when it goes off.
Car horn or a siren?
parking lights flash or headlights?
is there an LED installed in the dash, or a
"security" idiot light in the guage cluster?
is there a push button or toggle switch
under the dsah area or none present?

Let me know.

ALARMTEK
CARALARMINSTALLER.com