Adobe products can be difficult to upgrade, so I would use Adobe's own uninstaller to remove all traces of Flash Player from your system then re-install.

http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_14157

Uninstall, reboot the computer, (to make sure there are no remnants left), then visit Adobe again to re-install the Flash player.

I hope that helps.

Mark