Hi there and welcome.
When you try to access the internet on the problem computer, what exactly happens?
Ok, all instructions unless I say you do on problem computer.
Please click on Start->All Programs->Accessories, then right-click on Command Prompt and click on Run as administrator. Then type each of the command lines below, one line at a time, and press the Enter key each time:
netsh winsock reset
netsh int ip reset netshlog.txt
Then restart the computer and check if it now has internet.
Let me know the results please
ok, hope everything is ok