5stars:
the reason for your error is because someone else is getting that address....either manually or assigned.
Are you sure your sons computer is set to receive a address via DHCP?
make sure his tab on his network connections is set to receive a address automatically.
Make sure your other computers also are set to receive the address automatically.
right click on network places.....goto propertise....right click on local area connection and double click on TCP/IP......make sure all is set to receive it automatically.
****** you dont need to install the comcast software*******
If you plug your sons computer directly to the comcast modem instead of the router.......can he get on the internet?
If so...then we know your sons computer is working properly and its the router.....if not and you have your sons comp set up to receive a address automatically.......keep it pluged in and run the network wizard....remember its a direct connection and there is no need for username and pass.....and your dont have a proxy....
right click on internet explorer.....go to the connections tab and run the wizard......
If your son now can get on the internet connected directly to the comcast modem then we need to adjust the router.
reset your router by pressing in the button at the back.....this will reset it to default......now make sure the comcast ethernet cable is plugged into the internet slot and plug your sons into one of the other ports......try a different one that you were using.
all should be fine now and you will need to log into your router and setup a wireless secruity so others cannot use your internet.
If all fails......have you tried system restore options? Its rather easy and you will only lose files that you have done since the restore point your picked.
I hope you can get it to work......comcast I dont think will help you with it seeing how I think its the router or your sons setup causing the problem and not comcast modem.