Dell Alienware M11x Battery Problem

Hey guys and gals, I've had my laptop for about 5-6 weeks. Its a Dell Alienware M11xand I have never replaced the battery . The past 3 weeks or so the battery can only charge when the computer is off or in a low power state. If its on and plugged in it will still lose its charge unless its already at 100%. On a full charge without being plugged in it only holds its charge for about 1 hour on "power saver". This makes it extremely hard to use it as a portable device so i'm trying to find a way to troubleshoot the problem without having to buy a new battery or laptop. Unfortunately I need it for the next few months in some of my classes so its kind of urgent

Thanks for your help!
http://www.cheapaubatteries.com/dell-alienware-m11x.html