Hello,
Using IE8, please go to helpx.adobe.com/flash-player.html and click the 'Check Now' button. This will detect which version of Flash Player you have installed and display the version. If the version you are trying to install is lower than this you'll need to first uninstall Flash Player, using the standalone uninstaller, posted at Uninstall Flash Player | Windows, and then install the version you are trying to install.
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Maria