GPG errors when updating software packages

[michael_m]

Hi i am getting the following errors when i am updating software packages .

I am new to linux so it would be nice if someone would help me with it.

Thanx in advance.

GPG error: http://archive.canonical.com jaunty Release: The following signatures were invalid: NODATA 2
GPG error: http://archive.canonical.com jaunty-backports Release: The following signatures were invalid: NODATA 2
GPG error: http://archive.canonical.com jaunty-updates Release: The following signatures were invalid: NODATA 2
GPG error: http://archive.canonical.com jaunty-security Release: The following signatures were invalid: NODATA 2
GPG error: http://archive.canonical.com jaunty-proposed Release: The following signatures were invalid: NODATA 2
GPG error: http://ppa.launchpad.net jaunty Release: The following signatures were invalid: NODATA 2
GPG error: http://ppa.launchpad.net jaunty Release: The following signatures were invalid: NODATA 2
GPG error: http://ppa.launchpad.net jaunty Release: The following signatures were invalid: NODATA 2
GPG error: http://ppa.launchpad.net jaunty Release: The following signatures were invalid: NODATA 2
GPG error: http://packages.medibuntu.org jaunty Release: The following signatures were invalid: NODATA 2
GPG error: http://ppa.launchpad.net jaunty Release: The following signatures were invalid: NODATA 2
GPG error: http://ppa.launchpad.net jaunty Release: The following signatures were invalid: NODATA 2

Before when a error like this came it used to give KEY along with it and i used to add the key and then it used to work . But i cant understand what to do here.

Please help me ,
Michael.

[Partyboi2]

Open up Software Sources (System>Admin>Software Sources) and try changing you download server to another one.
What is you Internet connection like? If you have poor connectivity, it can cause this problem.

[michael_m]

My internet connection speed is good but i am behind my college proxy server.

Rest everything gets downloded and updated properly but always get those few erros.

tried downloading from another server still the same problem.