unable to surf www

Hi My aunt bought an Inspiron 530 with Vista (unable to buy XP.....) Computer is connected to a router directly to Internet. IP is obtained automatically by DHCP but Internet Explorer display white page, FireFox too and Thunderbird doesn't work too. it's possible to ping www.google.fr for example but no way to surf I've de-activaded firewall, but it doesn't work can you help me please ? thanks