I have lived with this problem but would prefer to sort it.
The alarm on my 98 reflection will go off at random. No 4 beeps as I have seen mentioned on other threads. It might be after 1 hour or 12.
I have bought a new car battery, checked the in car sensors. I have even tried pressing the alarm button to disable the cockpit but to no avail.
So to avoid problem, I now shut all doors except drivers side passenger door and reach in and press down the door lock to activate the central locking. then close remaining door. When returning to car at least I can open on the keyfob.
As I said I have sort of got use to it now, but wife did lock keys in car once using this method (dont ask!) and after getting spare key to unlock, spent a whole day repairing the drivers door when some useless dude tried to help wife with a piece of metal!
On the basis that wife will do it again (they only remember the important things in life - like when is the next holiday) would like to sort.
right coming up for fresh air now
bernie400