@sxg75: changing sudoers manually would be sufficient to doesn't get more problem, you can find more info on howto to fix the prerm script on the project page here : https://garage.maemo.org/projects/wizard-mounter/

@quingu: the problem is only when you uninstall wizard-mounter-1.5.4 , because when you uninstall dpkg execute the prerm script that (only for the 1.5.4) corrupt your sudoers file.