I had a rash of these failures. It was the trial version of Norton expiring and I can't explain why Symantec chose to kill the internet connection when it expires.
Use HIJACKTHIS to see if any norton or symantec software is still installed.
Windows 7 with current updates. IPv6 & Quality of Service not enabled. IPv4 set for auto DHCP & DNS. Can ping router and 220.127.116.11 and 18.104.22.168 OK. Can not ping www.google.com. Have reset winsock via [netsh winsock reset catalog] and [netsh int ip reset reset.log]. Have un-installed IE & re-installed. Have uninstalled & reinstalled network adaptor drivers. DNS server's status is good. Set only DNS to 22.214.171.124 (open DNS). Firefox can not access Internet either. Have set up new user & it can not access WAN either. Firewall is off & security software (ThreatFire & Immunet) are disabled. No proxy server. Ran CCleaner cleaner & registry scans. 'Diagnose' option on network adaptor could not identify the problem.