Thanks both. I tried it, but haven't quite got it right yet.
The Pause key did keep a screenful there to read, but wasn't sure how to let it resume, and pressed Pause 2 or 3 times (Is it a toggle?). Things then resumed, but landed in the dialogue screen offering Safe Mode etc. I selected Normal, but it hung once the Desktop background appeared. A reset then got a normal startup.
I'd pressed PrintScreen when things paused, but didn't know where to fetch the image from, and the clipboard was empty.
Have to go now till tomorrow evening, but will experiment again tomorrow.