Several users have reported an issue in which various Web browsers (Internet Explorer, Firefox, Google Chrome) cannot connect to websites despite the presence of an otherwise valid, working Internet connection.
Many users find that, when this problem occurs, they can ping the network, access email and perform other network functions, but browsers are dead in the water.
Disable link scanning in antivirus/malware software The number one cause of this issue is problematic link scanning functions in various antivirus/malware software packages. Try disabling any link scanning components, then restart and check for Internet access.
For example, you can disable AVG’s link scanner by clicking on the AVG icon in the task bar (lower-right hand corner) then selecting “Link Scanner” and unchecking the “Enable AVG Search-Shield” box.
Look for a similar Web “link scanner” or “web shield” component in your antivirus/malware package and temporarily disable it, then restart your computer and check to see if the problem still exists.
Remove conflicting antivirus/malware software Conflicts created by the presence of two antivirus or malware packages that duplicate each other’s functionality can cause this problem. Install one, and only one strong anti-malware package. The presence of multiple packages can create conflicts that decrease system stability and can actually make your system more vulnerable.
First, uninstall all antivirus and malware programs from your system, then reinstall one, solid package and check for persistence of the issue.