Do you have the MS Office extension installed in Firefox? Do you use a donwload manager? Your error report does not include a list of your Extensions - please check '''about:addons''' (use the address bar) > ''Extensions'' for what you have installed. This sounds like a case where Firefox is attempting an external operation that cannot be reached, which causes everything to freeze up while the browser waits endlessly. In addition to Extensions, please check '''about:preferences#applications''' (again, use the address bar) and search for the file extension you are trying to download. This will show what Firefox is instructed to do with the file. If it is set to open in some software by default, change the setting to ''Save File'' or ''Always Ask''.