Where you checked the box to turn on ICS, click the Settings button.
On the page that pops up, there should be a check box list of services.
Check any that say
DHCP
DNS
TCP
UDP
Web Server
and see if that works.
Those are the services your computer will share with the 360.
The DHCP should allow the 360 to receive an IP address, and the others...
I think will help. I'm not 100% sure they are really needed, but better safe than sorry.
On the page that pops up, there should be a check box list of services.
Check any that say
DHCP
DNS
TCP
UDP
Web Server
and see if that works.
Those are the services your computer will share with the 360.
The DHCP should allow the 360 to receive an IP address, and the others...
I think will help. I'm not 100% sure they are really needed, but better safe than sorry.