Hi XimeD- I'm sorry you are having trouble running Firefox! I would recommend fully uninstalling and then upgrading to the most recent version of Firefox by following these steps: * http://www.mozilla.org/en-US/firefox/new/ * Uninstall your current Firefox version. * Do not remove personal data when you uninstall the current version. * Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer. * It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling. * Your bookmarks and other profile data are stored elsewhere in the Firefox Profile Folder and won't be affected by a reinstall, but make sure that you do not select to remove personal data if you uninstall Firefox. * It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling. * Your bookmarks and other profile data are stored elsewhere in the Firefox Profile Folder and won't be affected by a reinstall, but make sure that you do not select to remove personal data if you uninstall Firefox. Good luck and thanks for using Firefox!