Saw a related question, disabled hardware acceleration, issue resolved. Still doesn't explain why I couldn't install, but that's ok.
Hi, glad you solved your own problem On the Uninstalling, removing it from add/remove or control panel/programs & features doesn't do it. In your case, glad it didn't since you ran the test, and Flash Player is working fine now(without the h.a)
If you ever need to Uninstall Flash Player, be sure to use the latest Uninstaller from Adobe since it changes each time a Flash Player Update is released.
You can always find the latest Uninstaller just be looking at a few threads here on the forum.