Hi Paul,
Try creating a completely new folder C:/AirNav Systems and cut/paste everything AN under Program files to this new folder - it's what I had to do early this year, or if you're not too worried about going back to square 1, delete everything AN related and check all files, then reload to the new AN folder - I've Win 7 64-bit and had problems with 3.13 until I did this. If you're after 3D - I've no experience or idea!