Do you mean when you've entered your password and you're getting to the desktop? Is it the gnome keyring asking for the password for network card? If so, I believe you can hit enter or cancel and it'll connect anyway if you've already set up a 'default' wireless connection.
Then right click on the status icon with the bars and select 'edit connection' then enter admin password if it asks and click on wireless tab, edit the connection and select the option 'Available to all users' and click apply and close. Then in the future it shouldn't ask again. It's some gnome thing that started happening a few months ago.