My '98 Jeep Grand Cherokee is automatically locking itself, often several times in a row. No one is pressing the lock button on the keychain, and it doesn't appear to be stuck. What's going on???"
This is a built in feature. It will lock itself once you hit about 10mph (I think). It will also lock itself if you unlock the doors, but then do not start the engine within a minute or so. Its a safety feature built in to lock the doors in case you forget.