I think I have read about an issue of this nature before. I will have a look and see if I can find it. It could be the cable, which I know is a weak point in the system (as the screen goes up and down the cable can rub).
You say you have recently bought the car. Was that from a dealer? If so, you are probably covered under some sort of warranty.
If not, you might need to go down the dealer route, unless you are handy with car electrics.
You could try a system reset, (RT6) press and hold the eject button until the system shuts down (any disc in the slot will come out & go back in). This will reset the system, just in case there is some kind of glitch, but it is probably not going to solve the problem.
You could also try updating the firmware. You should do a search on here for your particular system, RT6 Or NG4, and make sure you have the latest software.
Once you have done all you can, if the problem persists, it is more than likely going to be a dealer thing, but there are a few things for you to have a go with.
With a bit of luck, one of the above may help.
