DNS Probe Finished

Hello!
I get a "DNS Probe Finished" error every time i try to connect to a site.
I've tried to:
i) change the DNS manually
ii) release/renew ip
iii) reboot my modem
iv) Re-install my browser

When everything failed i tried to connect to another network and everything was working properly. Finally i brought a friend's laptop home and the same problem occured.
I am really desperate and out of ideas , PLEASE HELP ME!:(

PS: i haven't tried to connect via Ethernet , i dont have a cable.