Found this thread which looks like it might help. Any other ideas appreciated though.
I have just installed my very 1st Carputer and when the screen works it's running very well. I have the 7" lilliput screen moulded into the dash and it runs fine for the first 10 minutes or so after I start the car. However after that the screen itself works fine but the touchscreen stops responding. I don't think it's heat as it happens whether I have the heaters on or not.
Any ideas are massively appreciated as it's the only thing preventing the install from being 100% working.
Having to use a mouse whilst driving is virtually impossible!