NO pubkey in xubuntu 11.10 when i use apt-get update

Question

W: GPG error: http://download.opensuse.org  Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 85753AA5EEFEFDE9
W: GPG error: http://download.opensuse.org  Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 51AFC9B27331E9C4 thx 

Answer 1

_{converted comment to answer}

The error you see is due to you having added a OpenSuse repository.

Search in Dash for software sources and untick the OpenSuse repositories you see in the Other Software tab.

Close and the refresh Update Manager

Alternatively - from a terminal run

sudo apt-get update && sudo apt-get upgrade