I'd suggest that you check your main 'FeralHeart' folder for any Dou8le Particle files-They're 8asicly your usual particle files, only with a '_<Number>' in them-- any of these need to be deleted. If this doesn't work, try 'Running FeralHeart as an Administrator'.
It may depend on what account your on when it comes to the 'Run as administrator' thing--Try opening FH up right now, and if that doesn't work, delete the other FeralHeart folder /after/ checking it for dou8le particles, and re-install ono.