IIRC XP will require you to use an admin account to install Flash Player. Also check that security software is not blocking the install, and that you have the correct version for Firefox Browser. You will probably need to close Firefox,and it will be best not to run anything unnecessarily other than the Operating System when you try to install FlashPlayer. You will no doubt also have Internet Explorer installed, that uses a separate type of Flash Player plugin download, have you also downloaded and installed that ? See also [[Install the Flash plugin to view videos, animations and games]] ----- P.S. Similar comments would apply if it is Adobe Acrobat/reader that you are trying to install/upgrade.