If true, that is honestly one of the strangest bugs I've ever heard of!
Well, one suggestion is to check your textures folder (which should be located in C:\FeralHeart\media\terrains\textures) and see if all the textures are as they should be and not all african_grass duplicates. If for some odd reason they are duplicates, I wouldn't mind (if it was allowed) uploading a zip of just the textures themselves.
Another thing you could try would be going to your in-game options and switching your rendering engine between DirectX and OpenGL, and even try adjusting your view distance and/or anti-aliasing settings. What are your system specifications? Are you running Vista, 7, XP, Mac? Be sure to also give us information on your RAM and available hard-disk space, as it sounds like it could be a memory problem. (if you're running Windows 7, go to start and type dxdiag into the search box, then hit enter. Most of the statistics you need should be there in the system tab. Some information from the display tab would also help, as GPU specifications are important too. (It's the same process with XP, you just need the extra step of clicking on "Run..." after you go to start)
Hopefully that should help. :3