A couple days ago i was playing a game on the xbox, my box worked fine. About 4 hours after i was done playing I decided to play again. I booted my xbox with the modchip off and i got ERROR 7. With the modchip on ERROR 7. I then took apart my xbox and made sure the ide cable were properly connected at the 3 spots. Booted it up again and got the same error. I then took my modchip off (have a solderless one) and then booted it, still ERROR 7. I then replaced the original xbox hard drive and got ERROR 6. Then i reinstalled the modchip, and with the original HDD still ERROR 6. I then proceeded to change the ide cable. Still no success. I did check both hard drives and they are not dead. I then put the 120 GB HDD in with the modchip on and amazingly the boot screen came up with XBOX and with XECUTOR2 down on the bottom ( hasnt done this during this problem or with the regular MICROS*FT.) But it just hung at the screen. I havent been able to get that to come up again. It seems like i have tried everything and still can't get it to work. I would like to know of any similar experiences and how you fixed them. Thanks. Sorry for the long post.

Your HD is probably dead. Try booting with the chip on, the new 120GB HD, and use Slayers or something to format the new HD (if it's not formatted already)