Does it seem to happen when you type a capital Y as opposed to lower case? If
so, you are probably hitting the Ctrl key instead of the Shift key, which
triggers the Repeat command. What happens depends on what you last did.
Not to be nitpicky, SB, but that is what CyberTaz said. He said that perhaps
they meant to hit Shift-Y to capitalize the Y but instead hit Control-Y,
which is the repeat command.