Really weird... Not me, but one of my users. If she has a surface entity selected and goes to key-in a command, little icons with shortcut (I guess) letters show up on the tabs. "ET" for express tools, ""M" for manage, and numbers for new, open save, etc., on the quick access. When they show up, she can't enter the command she wants. Has to esc, and use the toolbar.
I've Googled the hell out of this, and can't find a variable, and I can't replicate on my system.