Navigation problem, please help!

[chemist]

I installed Navigation DVD drive purchased on e-bay on my 2002 ML320. The MB part number of the DVD unit is Q6820821. It works fine except when the car is warm after driving for a while. If you don’t turn it off, it will keep working fine no matter how warm the car is. However, if you turn it off and turn it back on again, it will not be able to load program (frozen on the initial image: picture of a ML). It will work again after the car parked for 30min (cool down). It appears that the program can only be loaded when the car is cool. If I taking the disk out and put it back in when the car is warm, an error message: “error reading, please check your disk”. The message will keep display until I disconnect battery and let car cool down for at least 30min sometimes overnight. I noticed that DVD drive get very worm after car getting warm. The disk also is very warm when I took it out. The DVD disk that I have is version 2005.1 in very good condition (not a copy). Is it possible the version of the disk is too new for this DVD drive? If someone is experienced with this, please help!