4) Could be a bad Ethernet card.
I'm thinking it's not the Ethernet card since it shows it is connected - showing duration - and 100.0 Mbps. For some reason I can't enter service settings for the IP address.
Open up command prompt and perform the following from computer with problem.
Enter this instruction at the command prompt and either copy/paste the info from it here or share the IP, Subnet, and Gateway info:
IPCONFIG/ALL
Additionally run the following instruction to see if you can ping to google
PING WWW.GOOGLE.COM
If the ping is successful then its not network adapter but another problem. If ping is unsuccessful then see if you can ping your router. Whatever gateway address is shown in the IPCONFIG/ALL output you will ping which is your routers IP to your local network
It might be 192.168.1.1 however it could be different:
PING 192.168.1.1