I've just attempted to open Synaptic Package Manager several times, without success. After I go into the Preferences menu and click on it, my cursor briefly shows that it's waiting or loading, but then it stops and nothing happens. I haven't had this problem with other applications that I can recall. I haven't tried anything besides just clicking on it in the menu; is there anything else I can try or any way I might be able to fix this problem?
An Authentication Required window for authenticating with your user password will pop up.
If that doesn't work start maybe the authentication-agent is not running. Run the following commands to run the agent and start Synaptic:
sudo /usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1 synaptic-pkexec