Auressel

So here's the area I'm trying to load into the GECK: http://i4.photobucket.com/albums/y146/auressel/Area.png Everything's named correctly, correct formatting and file sizes. It loads into the GECK's heightmap editor, but when I try to actually look at the terrain, it crashes. Is it simply an issue of too much elevation? (The area I'm working with is Summit County, CO, with elevation changes from 7500' to 13,000'+.)