I "upgraded" to GO620 wifi. I imported my customer POI files. Whenever I try to call up any of those, most times the device claims it doesn't exist if I don't give it the exact city or they are in the immediate area. Then, when I retry, it tells my that no POIs were found in that category. The only way for them to reappear it to reboot. So far, this GPS has been totally useless to me! I have transfered these same files to other TomTom units successfully.