Newly installed Mint15 (64). Installed language support for Russian, Tatar, Hindi and Tibetan. First everything worked fine, but (perhaps after I installed some new fonts using gksu caja?) now Hindi and Tibetan are not being displayed at all in Firefox, Thunderbird, and as the traditional little boxes in Pluma and in the language support window, whereas everything is perfectly displayed in Libreoffice. Furthermore, all other Indian scripts as well as all Arabic scripts are functioning (except certain characters in Urdu). Really puzzling, but hopefully there is some nice easy solution to it. Isn't there?
Tried to uncheck Hindi language support, reboot, check again - nothing. Also tried to specify the languages in question in the Firefox preferences.