update manager crashes

[Crystal]

Binary package hint: update-manager

Hi,

When I attempt to run update manager or install a package through terminal, I get this error message (or a similar one when I'm in terminal):

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/us.archive.ubuntu.com_ubuntu_dists_natty_main_binary-i386_Packages, E:The package lists or status file could not be parsed or opened.'

Help?

Thanks!