The first Xbox 360 I bought got the Open Tray error after a month or so. I put the disc in, and sometimes it would say "Open Tray", and I had to open and close the tray until it started to work. At first it was tolerable, but it only got worse overtime. I bought another Xbox 360 after it became just plain intolerable to work with. To make sure it does't happen again, can anyone give me advice on what causes this to happen, and tell me how to prevent it?