Hmm... does the map show the meshes? Such as trees, plants, and other normal items? It could very well be FH that is causing the problem, and not the map download.
What 'ave ye downloaded recently? Any new meshes, items, or maps? Other downloads could cause the problem ye are dealing with. Make sure to check y'er files in and out to see if anything is out of place. I am not really sure how to diagnose this without looking at the possibly corrupted files themselves.
Are ye able to give out this map download or is this a private map? If 'tis public, would ye mind shooting over the download link? If so, I could possibly tell ye whether or not 'tis y'er FH files or the map download.