door ajar and interior lights staying on

The door ajar light comes on, along with interior lights whenever if wants to. (even when all doors and back door/window are latched securely) while driving for a while, not all the time, and after I've gotten in to drive off it want shut off, sometime it lasts for hour or so before it goes off, even after i have gotten home, it has been taken to dealership twice, of course they couldn't find problem because lights were acting normal. any suggestions on what i could do myself. thanks Mark