CTRL ALT END

So my colleague decided to press CTRL ALT END instead of the usual CTRL ALT DEL. Smart not knowing what it does. We were not remoted in just trying to shut it down. After this happened a blue screen pops not like a blue screen brighter and lighter in color. He hit the power button held it down and nothing. So what does he decide to do now none other than yank the power cord. Well the LED on the MOBO letting you know your MOBO is getting juice decided it wanted to stay on for oh idk a good minute after we yanked the power cord. Does anyone first know what CTRL ALT END does when your sitting at a logon screen (not remoted in)? Or maybe have seen this is issue? Thanks for any help.