Comment 19 for bug 243722

Ok here is how mine got fixed

To enable the proposed archive for hardy add the following line to /etc/apt/sources.list:

deb http://archive.ubuntu.com/ubuntu/ hardy-proposed restricted main multiverse universe

or go to System -> Administration -> Software sources and tick the hardy-proposed box under the updates tab.

close amsn window

Now open a shell and type sudo apt-get update

Now type sudo apt-get install amsn

now open amsn. If it works then go back to the the start and un-tick the Hardy-Proposed box
now in that same shell type sudo apt-get update to get back where you were.

If it works for you please keep updating this thread

By the way I am running Ubuntu Hardy.

Thanks to Adri2000