Thanks for the link. The updater worked this time. My 7500 was V3.8.14 and now has been updated to V3.8.16. Unfortunately that didn't fix it. After installing the update, the calibration screen popped up, but when I tried tapping on the 'X' (upper left corner) nothing happened. In fact, tapping any place on the screen has no effect. It would appear this unit is defective. Unless anyone can think of anything else to try, I'll make arrangements to return it tomorrow. Most unfortunate!