Weird. My first advice is always to check the folder to make sure you have all of the required folders; exports, media>items, materials, models, objects, overlays, particles, terrains, textures, You should have them all but just double check for me. If you do, my next advice (if restarting the computer didn't work) would be to completely erase the game. Uninstall from Control Panel and go to your disk and make sure to completely delete the FH folder. Restart your computer. Save all of your mods and stuff separately if you don't want to go tracking them down later on. Download and install the game again, and just for good measure, download the markings again just in case you got a bad download. Put the markings folders in the FH folder as they need to go and be sure to replace everything. You shouldn't have to restart, but I would also restart one last time just to make sure. If that still doesn't work we can try something else.
Hmm. I know you've likely already done this, but just copy and paste everything from the download folder to the FH folder one more time and be sure to replace everything it asks you to replace. Now, you shouldn't have to restart your computer but do so just in case. Sometimes a simple reboot is all it takes. Let me know if it still doesn't work. Are you using windows, mac, or linux?