hi,
you apparently added debian-multimedia.org site to your apt/sources.list, but didn't import the gpg key. all packages are authenticated using the gpg and missing key leads to this error message.why is w32codecs not part of standard debian apt sources lists, it says WARNING: The following packages cannot be authenticated! w32codecs
issuing aptitude install debian-multimedia-keyring; aptitude updateshould help here. it's actually wise to install all *-keyring packages if they are not installed already.
-- Lubos _@_" http://www.lubos.vrbka.net