Permanent removal of an old WPA2 key stored in Window7 Pro

How can I permanently remove an old WPA2 key so that it does not keep reappearing? I changed the key in my client’s WAP, but the key stored on the Windows 7 Pro machine keeps going back to the old one every time his machine is rebooted.

I can go into Networking/View Wireless Networks and click the Properties/Advanced tab and change it to the correct key so that I can connect, but the old one always comes back after a reboot and I have to go in a manually change it again.

I’ve deleted the connection, as well as uninstalling the wireless adaptor and letting Windows reinstall it at reboot, but nothing works.

Is there a Registry key somewhere that I can delete or edit to make the new/correct key stay in permanently?

HELP!

Thanks much.