I am having this problem since this morning; nothing new has been installed in the last few days, except possibly automatic Mozilla updates. I can ping any website from the CMD prompt. I can access my mail through Thunderbird. I can mount a remote drive, but I cannot connect to an HTTP server on the same machine, using any browser (IE, FF, Chrome). Skype works, too. Network diagnostics shows that FTP and HTTPS connections work, but the HTTP test fails with the diagnostics: warn HTTP: Error 12029 connecting to www.microsoft.com: A connection with the server could not be established error Could not make an HTTP connection. Indeed Https connections do work from any browser, only http ones are affected. The most bizarre thing is that when I reboot, for a few minutes everything works fine, and then I get the same problem. Any advice? Thanks!