]. Hard reset is the immediate first aid for any unit behaving erratically. If that doesn't work, give it a very stern talking to.
If you've modded it for 4D i wanna buy it. Just a typo i guess. The '3D' map is for city building and landmarks and will only show in a big city environ. Put it in simulator mode and set the location to a large city and have a navigate around.
BTW, the 765 isn't really 3D capable. The '3D' images in your gmap3d.img are a semi-transparent overlay to the detail map and are more like the way perspective drawings are on paper than actual 3-dimensional images per se. This is from a 765 running TWN firmware, so the screen is a little different to your NA unit but the buildings and landmarks display the same:
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Bu**er! I see you've edited, makes my witty comment kinda sad now.