IE/Firefox not working anymore on Vista

Hi, I suddenly got an internet browsing issue in Vista.

I can ping from Vista any web site, but when it comes to browsing the same site using either IE or Firefox, I get “cannot display web page”.

This behavior has started suddenly after some automatic updates on 9th of Oct. Also, I have replicated the problem with the firewall and anti-virus/spyware turned off.

Any ideas are highly appreciated. Thank you.