Hi All
I had my superb satnav unit go awol and was not wanting to flog out big money for a new unit so I got a retrofit radio and CD player fitted for £132 and I shall rely on my garmin if I want to go anywhere. The point of my post is that when I got the old unit home I took it apart down to the last little bit and examined it for any visible faults. I found that the backing on one of the motherboard chips had fractured. It looked to me like a split caused by heat build up. I have had some experience with computers and know that heat will kill a lap top or desk top machine over time if it is not ventilated. The unit had (in my opinion) a very small extractor fan and a little heat sink. This is probably adequate if the unit is in the open but confined in the dash board where very little air circulates is asking for a problem. Just a thought but it would explain why these units expire around the three to five year mark, depending on the cars usage.