Help! Why does our alarm keep going off on our 2010 Swift Challenger 570? Changed it from all alarm to just motion sensor and it went off for apparently no reason at 9.40 pm last night. It wasn't windy and our cat, who has been known to leap onto the roof, was fast asleep in her basket! We have noticed lately that it does go off for no reason, should we get it looked at or is there a battery that needs replacing. All new to us, so any advice gratefully received. Thanks. Lisa and John.