Can't open iMessage anymore

After my friend sent me an extremely long message through iMessage (easily more than 200 lines), I managed to see the message, but then iMessage froze. After force quitting the app and opening it again, It crashed again, and to this point in time I have not been able to successfully open it since. This all happened on my new iPad 3rd gen. I'm considering restoring the software, but I'd doubt that would fix anything because the same thing happened to both my iPod touch 4th gen and my friend's 3rd gen iPod touch. (Both iPods are running iOS 5.1.1, while my iPad is on iOS 6). Any suggestions as to how I can fix this? (My iPad is still under warranty, so I can take it to the Genius Bar if I have to).