I got a very big problem with sticky keys today when playing The Witcher 3.
The pop up box showed up and I pressed enter by error and the dam sticky keys option froze every keys for good.
Only a sound and no more functional keys even if I rebooted the computer. No possibility to reverse that back. Tried to unplug, switch the keyboard, etc....
It is a Windows 8.1 bug I am pretty sure of that. Enable, disable sticky keys in the control panels options don't even work.

The ONLY solution is to ERASE the entire registry node [HKEY_CURRENT_USER\Control Panel\Accessibility]
And restart the computer.

I lost many hours on that.... I hope that can help.