If my memory serve me right the Lukas cams record files 3 minutes long, and there is no changing that in the software ( at least not for my LK-7500 )
Parking mode is only usefull if where it is plugged in have power while parked, or you have done a permant wirering of it, otherwise it just power down when you turn off the car. ( little display on back write good bye if its shutting down )
But it do sound funny that it do stuff while driving down the freeway, it might be the plug comming loose in the ciggy socket, i had my Lk-7500 do that, but it just stopped recording. ( proberly as i have parking mode disabled )
What firmware are you using ? ac31 is the latest one for your camera if its the old regular one, and oa31 if you have the 7900 ARA model.