Passenger door speakers cutting out

I have a 2003 S60 D5 with Pro-logic. Everytime I use the car the speakers in the passenger front door cut our after about 10 minutes of driving. It is always after about 10 mins (perhaps when the head unit gets hot???). Has anyone else had this problem and is there a fix for it (other than shelling out for a new head unit - no doubt very expensive). Also, am considering the iPod adapter. Is it any good and can it be easily fitted?

I had similar problem. Check the wires connecting the door with car body and connector in the door, something must be broken. It's only normal that head unit warms up but it shouldn't switch off any speakers.

Thanks for the tip. I'll strip the passenger door out this weekend and let you know the result.