I have had the same fault being reported by the Mint 14 update manager for some while now:
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/packages.linuxmint.com_dists_nadia_main_i18n_Translation-en
E: The package lists or status file could not be parsed or opened.
E: _cache->open() failed, please report.
Preferences are set level 1-3 visible and safe. All settings other than preference levels are unchanged from the nadia installation.
I do not profess to understand what is going on under the skin of update manager.
Where do I start ?
Thanks in advance