Weird Problem with the door locks and anti-theft

I have a 95 Econoline E-150 conversion van. I can lock the doors but about 1 hour later it automatically unlocks the doors without using the key fob or the inside switches. The inside unlock button on both the passenger and drivers side does not work but the lock button does. When you lock the van and it unlocks itself, if you open any door then the alarm will sound. I've tried a search to see if there was a solution to the problem and any help will be greatly appreciated. Right now i'm stumped.

I've got the same problem. Alarm goes off when I open the door. When I start the car. Just driving. When I lock it and walk away, it sometimes unlocks itself. When the inside lock buttons work, the driver's door will lock, but not unlock.

Sometimes when I stop the van and take out the ignition key, the key-in-ignition chime keeps chiming until I fiddle with the ignition switch. Could the switch be causing all of these problems?

Plus, my airconditioner works sometimes, sometimes not. And the radio clock occasionally resets to 12:00.