Well Boggin, finally narrowing issue down to the SSD drive. After removing it to copy the data, the same freeze occurred during the copying (Via USB) to my stable W 10 PC. So multiple reboots and got the job finished.
Next I fitted the spinner back to the laptop, all well, then booted from the W8.1 ISO, thanks for the link, and did a full reset. Now waiting for the 150 updates! As it happens my Key was accepted and there was a happy ending to this adventure.
Reading up on SSD freeze I saw this issue crops up a fair bit, users posting the following:
"Then, although the cursor moves, everything has frozen. Clock stops, browser freezes, can only hard reset to start again"".
"Hi. Got a new SSD, WD Blue 250GB, and it constantly freezes my entire PC when transferring files to it through either download or just moving files to it from elsewhere on the PC. The freezes are seemingly random. When the freeze happens the transfer speed usually drops to 0 (sometimes it doesn't even register that and it just stops) and everything on the PC becomes unresponsive, including task manager. This forces a hard shutdown and restart using the power switch".
A good article to add to your database:
https://www.partitionwizard.com/clone-disk/ssd-freeze-up.htmlthanks again for your persistence in helping me, learning curve in vertical !!