A cross over cable would not be bad... it would just get no signal...
Check this:
1. The port next to the WAN port could possibly be shared with the WAN port... don't use that one.
2. go into the router (192.168.0.1) with IE and the login is admin password blank, and look at your WAN settings. if you are showing an IP address there then you should be fine.
3. try to ping a website ( ping
www.google.com ) then try to ping an ip (ping 192.168.0.100)... it is strange to me that with DHCP enabled your PC has ip of 55 but xbox is showing 100. it seems as if your pc is not setup for dhcp, however all the settings are correct if those are the settings.
4. Put anohter DNS server in your PC (4.2.2.1 - 4.2.2.4 are ips of verizon DNS)
5. Check to make sure that the router is in fact turned on as a router. if it is not then that would explain why it would turn off when you connect another machine.
6. check that all the cables are plugged into the correct ports (try not to plug into the port next to the WAN connection... i have seen it where those are shared... one for switch and one for routing.
other than that i really don't know... sorry
