GPG error: http://ftp.tku.edu.tw natty InRelease: The following signatures were invalid: NODATA 1 NODATA 2GPG error: http://security.ubuntu.com natty-security InRelease: The following signatures were invalid: NODATA 1 NODATA 2GPG error: http://ftp.tk

GPG error: http://ftp.tku.edu.tw natty InRelease: The following signatures were invalid: NODATA 1 NODATA 2GPG error: http://security.ubuntu.com natty-security InRelease: The following signatures were invalid: NODATA 1 NODATA 2GPG error: http://ftp.tku.edu.tw natty-updates InRelease: The following signatures were invalid: NODATA 1 NODATA 2Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 (20110427.1)/dists/natty/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
Failed to fetch cdrom://Ubuntu 11.04 _Natty Narwhal_ - Release i386 (20110427.1)/dists/natty/restricted/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
Some index files failed to download. They have been ignored, or old ones used instead.

E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/ftp.tku.edu.tw_ubuntu_dists_natty_main_i18n_Translation-en
E: The package lists or status file could not be parsed or opened.
E: _cache->open() failed, please report.

helpppppppppppppppp

bzip2: (stdin) is not a bzip2 file

To solve the 'no Package: header' problem please see

https://answers.launchpad.net/ubuntu/+faq/1591