Interesting one today...
I appear to have for no apparent reason, lost my main windows taskbar. There is always a space on the desktop where it should be, but it's just not there.
I have tried toggling auto-hide, positioning. Even restarted to make sure it wasn't a crashed application.
Charms, still works. Can still get to the start screen by using the windows key or ctrl+esc, can still get the windows key +x prompt