When the car is left for more than 24 hrs. without running, on the next start the engine starts but the alarm goes off as well. Go through the motions, turn engine off, press detented button on fob, alarm stops. Start engine, all o.k. My first thoughts are battery, the car is five years old and I do a lot of shortish runs with the lights on. Anyone got any other thoughts. Thanks.
Andy.

 

sounds very much like it could be the battery. It does weird stuff to the alarm. Have you ever had the battery run completely flat? They never really recover from this and it would make a dodgy battery causing the problem very likely.

5 years would be about the limit for battery life - with winter coming you'll be sensible to get a new one anyway.

 

Mine's 6 years old now and went completely flat last week.... couldnt even pop the boot or turn the interior light on! Since then its been doing weird things to my stereo (amps often wont power up at all, some kind of failsafe I assume) and feels quite hesitant even after a long drive... Time for a new one!