Or maybe it was the Windows-U key command, which launches Utility Manager. It's an accessibility feature not listed in the control panel. And after launching it with Win-U, the text-to-speech engine starts squawking at you, increasing the distracting WTF-factor as you fumble to turn it off.

But read the above linked article for some really fun info about utilman.exe. Win-U will launch it even before you're logged in, running as the SYSTEM. Replace utilman.exe with a malicious script and you've got yourself a backdoor that's only two keyboard presses away. Nice.