Comment 6 for bug 137625

Ok before going deep, let's try something simple : update and upgrade feisty :)
It will download the list of the last updates available and then install them.
In order to do that, go to the synaptic package manager, click on "Reload" or "update" at the left of the toolbar (i'm guessing the name from my french localization) then click "upgrade" just at the right.

The problem sounds like you have a mismatch between two librairies (which shouldn't have occured) so maybe a simple upgrade will do the trick.