I live in India and use to connect to internet through BSNL modem. All sites open and loads without problem as this site is opening without trouble but when it comes to some secured connections such as gmail and facebook firefox or any other browser just gives looking up site and looking up site and site never opens,but when I connect it through windows on the same connection it opens ,I have tried by disabling Ipv6 and some methods given in internet but did not work and my ISP says there is no problem in the connection,so how can I rectify this problem please help........

Take a look at this:

I think it may solve your problem.

HTH,

problem still persists...