Windows 7 Security Pop Up Asking For User Name And Password?

I attempt to connect to my wireless broadband connection but when i click 'connect' a windows security pop up arrives stating that I need to provide a username and password for 'Network authentication'. I dont have these nor do I believe that I have ever included these perviously. This action has only recently appeared and I cannot 'bypass' it. I have other computers linked to the same wifi connection and these are operating just fine (the problem computer runs Windows 7 and is the only one with Win 7). So at least I know that it is not the internet connection itself.Maybe not of any importance but this problem only occurred after the unit ran out of battery power and has not been able to access my broadband service since the subsequent recharge.I have visited Win 7 Network centre on the computer to attempt to establish the problem (it recognises I have one) and been through all the troubleshooting options but no resolution.