You could also try re-installing the game, or if you don't want to go through all that again you could also try opening the game another way. For example, if you have a desktop shortcut icon that you use to open up feralheart, try deleting-and-replacing the icon or moving it back into the Feral Heart folder and try opening it that way.
Like Suragaha said it could also just be that Feral Heart isn't directly "compatible" with the other programs or windows you had open. For example, my computer crashes if I open Minecraft and Feral Heart at the same time.