Sometimes running the updates in the Update Manger results in the following error:

Could not initialize the package information.
An unresolvable problem occurred while initializing the package information.
Please report this bug against the ‘update-manager’ package and include the following 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-amd64_Packages, E:The package lists or status file could not be parsed or opened.’

A similar error occurs while running the apt-get update command in terminal:

Reading package lists… Error!
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_natty_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.

There is a one shot solution to the above errors. Open the terminal and run the following commands in the given order:

sudo rm -rf /var/lib/apt/lists/* 
sudo apt-get clean 
sudo apt-get update