[ALUG] APT GPG error

Does anyone know why I get the following warning message whenever I use apt-get update? W: GPG error: http://mirror.ox.ac.uk unstable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 010908312D230C5F W: You may want to run apt-get update to correct these problems Is it to do with the mirror.ox.ac.uk mirror? Or is it my set up? I also get a warning when I use apt-get install and upgrade that the packages can't be authenticated which I assume is another symptom of the same problem. Does anyone know what it is? Cheers, Richard --------------------------- Richard Lewis Sonic Arts Research Archive http://www.sara.uea.ac.uk/ ---------------------------