Hi , Its likely you have a faulty charger putting too much voltage out , or , your car cigarette charger socket is dirty or similar causing intermittent supply and resulting in voltage spikes going through the charger and into the TomTom .... or ... spikes caused when starting your car whilst the charger is plugged in. The tomtoms are very sensitive to any overvoltage and it blows 2 IC's inside the TomTom. The car chargers are also known to put out overvoltage when they go faulty , it's quite common. Some car alternators dont regulate their voltage very well at the point of starting the engine so it's probably worth having this checked by an auto electrician. Cranking the engine cna also cause the starter motor to act like a generator just at the point where the engine fires and this then results in a voltage comming back out of the starter motor and into the cars wiring. Your TomTom charger should cope with this but it is possible that any spikes manage to get past the charger and into the tomtom. if you have had one TomTom blow using any particualr charger unit , then don't risk using that charger on a different TomTom uless you have that charger checked for correct voltage.
Good luck.

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For the guest comment .............. The Blue Tooth will not have caused the problem you are reporting , thats just a coincidence. The problems of having buttons highlight themselves and the touch screen not working properly is a fault with the membrain on the tomtom screen . Could be a fault on the membrain or just dust and dirt particles trapped under and around edge of the screen bezel ( plastic screen surround ). Try clipping out the bezel and see if theres any dirt around edges of screen . If there is , be careful how you clean that dirt / dust out. ... Good luck