Make an Explorer, not Home, backup. Ensure hidden files/folders are showing. Then format your unit. Don't use quickformat. Then restore the backup.

Does it help?

__________________
TomTom 720--NA Map 850--WCE Map 840--NZ Map 835--App 8.351

 

Also, try deleting the mapsettings.cfg file in your map folder. Depending on your unit, it will be in the "North_America" folder or the "USA-Canada-Mexico" folder.

__________________
Current Tomtoms:

GO 740 app 9.054 (weekdays)
Map North America 2GB 850 + full POI + map subscription
+ LIVE services

GO 930 app 8.302 (weekends)
Map North America 850 + map subscription
Map WCE_2GB 825
+ PLUS traffic + Fuel prices + free safety cameras

HOME 2.7.4.1962 - WinXPproSP3

Prior Tomtoms:
Go 720, Go 510, One Limited Edition, One 2nd edition (all sold)