Update not working, says it has "unmet dependencies"

When I try to run standard upgrades, it tells me that an error occurred and I should try to run the package manager. (I am using classic by the way). When I do, it give me this:
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/extras.ubuntu.com_ubuntu_dists_natty_main_i18n_Translation-en
E: The package lists or status file could not be parsed or opened.
E: _cache->open() failed, please report.

It gives me the same when I run it from the command line, the update manager, and if I try to get another package.
I cannot install anything else, please help.