Anti theft system reset?

Sometimes my alarm goes off for no reason. When I try to reset it, it does not always work. I can hit the disarm button on the remote and it will continue to intermittenly flash the lights and sound the horn. It will beep and flash about 3 times, stop then do it again 1 time, etc. I will start the car and sometimes it stops sometimes it continues for about 5-7 minutes. Then it stops. It may do this a couple times a day then it wont do it for a week or so.