Two Identical Devices. Flash Works on One, Not The Other. Suggestions?

I have two Windows 8.1 with Bing tablets in my household. They're both running IE11 version 11.00.9600.

They are both just two weeks old!

Unfortunately, one of them was infected with adware and browser help objects but as far as I am aware is now clean. Both Windows Malicious Software Removal tool and Spybot have run full scans and find nothing. I'm no longer seeing pop-ups or any adverts in the browser.

Just to be sure, after running the scans, I also reset IE to its default settings through Internet Options --> Advanced --> Reset.

The Flash player version is 16.0.0.235.

When I "Manage AddOns", shockwave is installed and enabled.

In "Safety", ActiveX filtering is OFF.

As far as I can see, all other settings on both devices are identical.

However, on the previously infected device, no matter what, when I  try to play a flash video I am informed that Flash player needs to be installed. Adobe's help for Flash tells me that the player is Disabled. All the settings\options I can see are telling me it is both installed AND enabled. The second device streams from the same website (BBC iPlayer) perfectly.

I'm assuming that there must be a registry setting somewhere that is not being reset no matter how many times I change the settings in IE and/or restart the device. I would love if someone could offer some advice that could fix this anomalous behaviour as it is now officially driving me mad!

Looking forward to some expert hand holding on this...