I have borrowed a fiends TomTom GO920 to take on holiday to Florida. It works fine in Uk but when I insert the TomTOm USA and Canada SD card I cannot get beyond the opening screen. It just freezes on me and I am unable to even turn the TomTom off unless I press the reset button in which case it turns off but doesn't resolve the issue. Would really appreciate help to overcome this issue. Many thanks.