@zsc and in7ane: Actually, I'm on XP. But I did try zsc's idea of using winrar and it worked. Thanks. However, I'm still getting the error when I click on "geodata" button once inside gmdl tool.
I was able to find a geodata file of CA on a thread. But how it this functional/practical? I was able to find a location but I'd like to know how to get to that same location from wherever I am using GPS. Kinda like getting directions. How is this possible? Is there anyway to get turn-by-turn directions?