Iv'e lost the small button icons (Acad?) on my C3D ribbon. They are blank. Also on all my other ribbons the automatic description that activates when I hold my cursor over the button no longer responds. And when I click on the larger Civil Icons they do not respond. When I type "ribbon" on the command line nothing happens. It doesn't go away and it doesn't reappear. How can I reactivate my ribbons??? HELP!