Update manager error - The following signatures couldn't be verified because the public key is not available

Q : Update manager gives error :
" W: GPG error: http://ppa.launchpad.net hardy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 248DD1EEBC8EBFE8 "

Ans : sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 248DD1EEBC8EBFE8



Sources :

• https://help.launchpad.net/Packaging/PPA#Adding
• http://www.uluga.ubuntuforums.org/showthread.php?t=1083516&page=2

Done.....!