To fix this issue you need to go to your ADSL Router page.

To find your router address

type CMD in run box or open command prompt from Accessories -> typing IPCONFIG in command promp and look for your gateway address.

Type the gateway ip-address in your browser and login (normally Username : admin, password : admin or password). Then select "WAN Settings" and use automatic logon, type in your ISP username and password and click on Save.

There you go.... Job done. If you have any questions please don't hesitate to ask me.