If you simply enabled the guest user, that may not be the best test. I don't think the guest account saves anything to the drive. and doesn't let you do a lot of things. Create another account (which could be an admin, if you choose to do that). Log out, then log back in to that account, then test again.
But, I suspect that the issue is system-wide, so try removing a couple of relevant .plist files in the main Library, then restart to your regular user.
Files would be in /Library/Preferences.
com.apple.BezelServices.plist
com.apple.HIToolbox.plist
com.apple.keyboardtype.plist
(you might not see the last one, so ignore if you don't see it)
system would need password to trash those files (probably)
I would do a shutdown, start, rather than a simple restart. That ensures that hardware is reset from cold (just an old habit of mine, but I find it works for my uses
) and that the .plists get recreated on next boot.
(If you do create another account, you can simply leave it for some later use, or delete it when you are finished with testing. It takes up very little space, and comes in handy for occasional quick tests.)