Xbox 360 Being The Useless Junk It Is..help?

[Gradon]

Okay so here's the deal.
When I connect my Xbox 360 to my Laptop via internet cable it would connect to the internet. Ever since...I dunno, July 2007, it just...never worked, my computer said "The LAN connection has little features and there maybe problems with it", and the Xbox 360 trys to connect...1 second later: "Some profiles could not be signed in to Xbox Live. There may be a network problem or a profile is not valid. Test your connection or recover your profile from Xbox Live."
But I have no idea why it STOPPED connecting through LAN, do you guys have any idea why or what is happening?

[Carnivol]

Maybe you told your computer to stop handing out IPs upon connection with devices.
Maybe you turned off network sharing/bridging on your computer.
Maybe you fiddled with your Xbox' network configuration when it had pre-set settings for your network.