Mozilla fixed several security issues in Firefox 47.
Not upgrading Firefox to version 48.x meant that the browser remained vulnerable to those security issues.
Mozilla's reason for stopping the distribution of Firefox 48 for Windows was an incompatibility of the program version with Websense products.
The product mentioned explicitly in the context is Websense Endpoint.
NET CLR 3.5.30729) network.cookie.prefs Migrated true places.last_vacuum 1275493714 privacy.sanitize.migrate Fx3Prefs true security.warn_viewing_mixed false Organize Bookmarks''' That should open the library window.