O1 Accord factory alarm going off after idle for hours

[01AccordLuvr]

01 Accord has around 90k miles, with keyless entry factory alarm that has started going off for no apparent reason, usually after the car has been sitting and locked for 3-5 hours. Called several dealers and got the usual "bring it in for a look" , or to use the key to set and disarm the alarm to solve the problem.

Anyone had this problem, and is there some logical reason it has started sounding the alarm, and any cure? Any ideas??...the neighbors are losing patience with the horn blaring, as are we...pain in the @**!!

Thanks for your advice.