Synaptic and Terminal been failing with Natty on netbook

Hello everyone,

I have been having this problem on my netbook with Natty running. Synaptic, Ubuntu Software Center and the command line Terminal all fail at installations ( if not at other things that I havent observed yet).

when I use terminal to install anything (typing, say, sudo apt-get install banshee) I get:

Reading package lists... Error!
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/archive.canonical.com_ubuntu_dists_natty_partner_i18n_Translation-en

when I open Synaptic and enter my password, immediately thereafter the error window opens:

an error occured
The following details are provided:
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/archive.canonical.com_ubuntu_dists_natty_partner_i18n_Translation-en
E: The package lists or status file could not be parsed or opened.
E: _cache->open() failed, please report.

what goes wrong here? how can I solve this problem?

 thank you so much for your help!!

best greets and a beautiful summer!!