Failed to Update Unity Web Player on multiple browsers

When trying to run any web-based Unity project I receive an error stating "Failed to Update Unity Web Player". When clicking on More Details, it states that "A newer version is required but the auto-update failed."

I have tried reinstalling the web player using the normal installer, the 'Full' installer, the installer found in the .CAB archive, but none of these work. I have also tried using CCleaner to remove any old traces of the web player after uninstalling. I have tried downloading an archive of what the Unity AppData folder should look like and extracting that into my AppData folder and that doesn't work either.

So I'm all out of options! This has been occurring on Chrome, Firefox and IE11. I am using Windows 8.1 64-bit and I should add that the web player HAS worked before!

Any help would be greatly appreciated!