I have been reading this forum for a few months now. This is really my first post.
A few minutes ago my balls grew big enough to confirm what Opjose was saying about the Live modchip detection.
I have a moded box with an Engimah chip in it, but with all the original software on the harddrive. Until now I have only gone on Live with the mod off, I have never had any trouble.
Now, I am assumming that in your network connections YOU CAN connect to xbox live, not play, but connect or handshake.
I loaded up MotoGp from the Live disc with my mod off...xbox live came up fine. I then turned my system off and switched my mode chip on and rebooted with MotoGp from the Live disc. After you enter your password, Live will never come up and send you to the network troubleshooter. Which, will still detect all your network settings and handshake with Live. I turned my system off again, switched my modchip off, turned my system on, then loaded MotoGp from the Live disc....I connected to the Live game fine.....NO SERIAL NUMBER BLOCKING!!!!
Thanks to Opjose for the great work he did.