Now I remember why I had the stand-by/hibernate settings applied. If I shut the computer all the way down and use the button on the front of the case to power the unit up I get a black screen with a blinking cursor. To get past this I have to power down the printer (attached via USB2.0) sometimes the computer will continue to boot - other times I have to CTRL-ALT-DELETE to restart the boot.
I have just added (1 week ago) an external HD (WD Elements 1.5TB) and have to either disconnect it before shutting down or unplug it and go through the same process as with the printer.