Ubuntu: 'E:Encountered a section with no Package: header, E:Problem with MergeList

When you try to update your system with update-manager or synaptic or apt-get or ... you receive the error message

E:Encountered a section with no Package: header,
E:Problem with MergeList /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_natty_main_binary-i386_Packages,
E:The package lists or status file could not be parsed or opened.

(The filename /var/lib/apt/lists/... might be different)

This is caused by a problem in the local storage of the package directory.

There is a command that clears up all locally stored lists (which is part of the https://help.ubuntu.com/community/PackageManagerTroubleshootingProcedure)

Open a terminal (ctrl-alt-t) end execute these three commands:

sudo rm -rf /var/lib/apt/lists
sudo mkdir /var/lib/apt/lists
sudo mkdir /var/lib/apt/lists/partial

In most cases executing these commands solves the problem, and updating the system works again.