Try going into the particles folder and see if there's any particles with the name _01 _02 etc. In that case delete them and then try to launch the game again.
If there's no particles by that name, go into the ogre.cfg located in the main game folder. Open the ogre.cfg with wordpad and set the top row to a the rendering mod that it's not currently set to, save the text doc, then start the game again.
If that doesn't help, you should probably remove FH all together and then reinstall with new installers.