I uninstalled Firefox 3 from Synaptic Manager and installed Firefox 2. After this I could not install add ons - an error message showed "installLocation has no properties". Following the advice on this page, I deleted the ".mozilla" folder from my Home directory and restarted Firefox. The problem was solved and I can install the add-ons again.
I uninstalled Firefox 3 from Synaptic Manager and installed Firefox 2. After this I could not install add ons - an error message showed "installLocation has no properties". Following the advice on this page, I deleted the ".mozilla" folder from my Home directory and restarted Firefox. The problem was solved and I can install the add-ons again.