So I have an xobx slim 4g with a separately bought 250g hard drive connected up to an Asus monitor with built in speakers through a bluerigger hdmi cable. All of this set up is less than 3 months old. I got the problem when I tried to download forza motorsport 3 and 2 demo. I first tried to download the forza 3 but when I clicked download the xbox froze and reset itself. After it had restarted it displayed a message "cannot download" so thats when I went for the forza 2 demo and the same thing occurred. Now whenever I start the xbox and sign into live the system will restart after about 10 second no matter what i attempt to do in that time period. The things I have troubleshot so far is that the xbox will work without the hard drive connected, or if i do not sign into xbox live with the hard drive in. I have also cleared the system cache which did not fix the problem (which I did with the xobx not connected to live). I have no idea what to do next and am worried I will have to send in my hard drive for a new blank one. If anyone help me to find a solution to the problem I will very much appreciate it.