So I installed a new XBox 360 250 GB Hard Drive today and it doesn't show up in the list of memory devices in the System Settings. I followed the instructions listed on this site and removed and re-installed it and it still doesn't show up. Is there something else I can do except just removing and re-installing again because I've tried that 3 times. I've made sure to press it in so that it is connected, heard the click, pressed a little more just to make sure it is connected. I also tried installing a game on the hard drive as well to see if it just wasn't showing up in the list but it just gives me a message saying that there's no valid device installed. Thanks for your reply.