An unresolvable problem occurred while initialising the package information.

Please report this bug for the 'update-manager' package and try to include the following error message:

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