mepis-config was updated to 11.0.1 on 01/17/12 to reflect the change to a new mirror for the Mepis repos. When upgraded your sources.list will be backed up and a new one written. If you have added non-standard repositories they will need to be added to the new sources.list. The backup is in /etc/apt and is sources.list.dpkg-old
The new mirrors are:
If reloading the repositories in Synaptic or in konsole with apt-get update generates an error about a GPG key, do the following:
Open console and su to root. Type the command checkaptgpg. This command will look for the keys associated with the sources in your sources.list file, and install the keys.