Run the uninstaller (even if Flash is not listed in Manage Add-ons) and then reboot.
Next, go to: http://get.adobe.com/flashplayer/ and when you see the prompt, choose "Run" to install it immediately. Oh, and uncheck any third party installation options like the Google Toolbar / McAfee. You can install those any time.
Go back to Manage Add-ons and confirm that 18.104.22.168 has been installed.