I've been trying to get that achievement since I started my LIVE account, and game after game I've failed. I've tried and tried until now, I'm a Brigadier level 45. The only thing is, if I keep trying as hard, my rank will go down. Now that I have a high rank, I don't want to lose it by trying to get that last achievement. But Wow! I truly have deep serious emotional problems that are "totally worth answering. But, if it's enough to bring me mild stress while gaming, then it's enough to ask for help... or not.