If it has continued showing that error message, I would do what Feareh has suggested above.
If the game works perfectly now, I wouldn't worry. It may have just been the server spazzing as it occasionally does.
But you may want to check your Feral Heart folders for anything with _0 or _1 at the end of them. Check the folders at Feral Heart>Media> the Particles folder, Sky folder, and the Objects folder.