Touch screen and no map found problems

Dear All of you, I?ve bought TomTom GO 720 around two years ago (Application 8.010, North America 2GB map v710.1584). I?ve just online purchased latest map v840.2562 from TomTom one week ago. However I figured out that

----- If I use Application 8.010 or older, GO 720 cannot recognize map v840.2562 (TomTom Home can see the map in the device; ?Change preferences/manage maps/switch map? in the device cannot show the map

----- If I use Application newer than 8.010, GO 720 can use the map v840.2562 but the touch screen not works properly. I need to touch an option for 10+ times. For every touch, the option will be highlighted but not function (i.e. option ?Back? cannot go back). Please see attachment for screen shots.

I?ve called TomTom support many times but none of them can solve the problem. Please help me to fix the problem in order to have a workable GPS with latest App and Map. Thanks.

Below, I list all actions that TomTom support team and I did in these days (one line per action).

(1) Download App 8.302 manually to replace objects in the device (Result: App 8.302, map v840.2562, GO 720 can see the map but touch screen problem has occurred)

(2) Removed and reinstalled the application via TomTom Home (Result: App 8.351, map v840.2562, GO 720 can see the map but have touch screen problem)

(3) Save folder "LoquendoTTS" to desktop, hit ?reset? key on the back of device, format GO 720 and rename folder ?TomTom/Home? to ?TomTom/Home old? in PC. Restore folder "LoquendoTTS" to GO 720. Reinstall the Application and Map via TomTom Home (Result: same as (2))

(4) Removed and reinstalled the application via ?TomTom Home? (Result: same as (2))

(5) Download App 8.010 and replaced objects in GO 720 (Result: App 8.010, map v840.2562, no map is found in GO 720. Touch screen is fine, no problem. TomTom Home can see the map in the device)

(6) Restore my original workable backup (App 8.010, map v710.1584). Removed and reinstalled the new MAP v840.2562 via ?TomTom Home? (Result: same as (5))

(7) Manually delete all maps in both folder ?TomTom/Home? in PC and GO 720. Reinstall maps via TomTom Home (Result: same as (5))

Thank you

Interesting fault, I know this is going to seem a strange bit of advice but get a thin piece of card and insert it between the screen and the screen surround, run it all the way around the edge of the screen to remove any debris that might have fallen in the gap then try the new application again, the newer Navcore releases do seem to be slightly slower in terms of screen response but yours looks like something is pressing on the screen all the time.
This issue of dirt getting down the gap and causing menu selections isn't unusual but i have never seen one behave this way before, but its worth a try to clear anything out that could be giving the screen touch sensors an issue - Mike

FYI. Both TomTom Customer Service and Technical Departments could not solve the problem. Eventually they asked me to send back the old one and gave me a new device although the guarantee has been expired. The problem has been resolved.