I had a strange problem browsing the internet. Firefox refused to work, giving me a "connection timeout" on every website. Ping and dns resolved ok via the command line. Even more peculiar, Konqueror worked as well. So, did a google for a solution, and managed to find this:
of which it states:
"Try turning off IPv6 in Firefox. For some reason that tends to fix problems with Yahoo.
Type 'about:config' in the address bar and look for 'network.dns.disableIPv6' and toggle it to true"
Did that, restarted Firefox, and voila, it worked.