You appear to be on Firefox 20.x which is possibly correct. Windows Firefox should by now be Firefox 20.0.1 *Use '''Firefox button -> Help -> Troubleshooting information''' to confirm the actual version you are using. This article is old but AFAIK still accurate, and explains how to delete updates before they complete. * [[Updates reported when running newest version#w_delete-update-configuration-files]]_delete-update-configuration-files I am not sure what you are seeing that affects other programs. You may need to review settings on any security related software you are using, as that could be preventing or reversing updates. Also possibly other programs running whilst you update could cause problems. *[[How to fix the Update Failed error message when updating Firefox]]