If you have Windows 8, you CANNOT use IE 8, because Windows 8 comes with IE 10 preinstalled and it WON'T accept a lower version.
In addition, Flash Player for IE in Windows 8 is modified and embedded by Microsoft. It's "their baby" so to speak. It can ONLY be updated through Windows Update (in your Control Panel under System and Security).
Microsoft released a "Tuesday patch" November 12 to update Flash Player for IE10 and IE11 in Windows 8 and 8.1.
If you run the update and still have problems, see: http://helpx.adobe.com/flash-player/kb/flash-player-issues-windows-8.html for more steps to take.