I updated Firefox last week and since then am unable to open .docx files from Firefox. I have checked my Firefox settings, as well as my settings via Control Panel (using Windows 7). The dialog box opens up asking me which program to use, I browse and select Word, but then get the error message "this file could not be found." (I didn't have to do any of this pre-update.) Note that .docx files will still SAVE to my downloads, and when I then click on them from the downloads list I am able to open them. They open fine in Chrome.