issue with update manager

Hello,
I just found this problem when I started Ubuntu today.Unfortunately I am new Linux user and I don't know how to solve it.
Please help me.

Best regards,
Kolyo

Problem:
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/at.archive.ubuntu.com_ubuntu_dists_natty_main_i18n_Translation-en, E:The package lists or status file could not be parsed or opened.'