Short story... problem solved, except that in the end there wasn't technically a problem at all!!
Long story... yes it was video drivers causing the problems... another learning curve
After re-installing the root filesystem it would only boot to the desktop in vesa mode as expected. After making sure there was NO inkling of anything Nouveau, I downloaded the legacy NVidia drivers (dkms-nvidia96xx & X11-driver-video-nvidia96xx) and tried to switch over to them in XFdrake... wouldn't have any of it
. Bash said there was an NVidia module already in the kernel and aborted. On quitting it automatically, without any prompt, on its own, downloaded Nouveau drivers and installed them
Well bugger that, I went through the process again carefully in case I missed something but no, exactly the same response!
I was minded of a previous thread that when kernel 220.127.116.11 first came out, it wouldn't work with these NVidia legacy drivers, only Nouveau. Fine. Let's go back to a previous kernel. So I installed the earlier kernel, got rid of anything Nouveau, rebooted into the old kernel, checked the legacy drivers were still in place... XFdrake... went through the process again. Well I'll be damned, exactly the same thing happened again:
an NVidia module already in the kernel and aborted. On quitting it automatically, without any prompt, on its own, downloaded Nouveau drivers and installed them
So I admit defeat. There was only one thing left for it... to use Melodie's hammer on all things NVidia
Physically disabled the graphics card and in the BIOS in favour of the on-board S3 Unichrome adapter... problem solved
and now my LiveCD boots up to a desktop as it did before, but now I can see it!!!
(BTW, it also expalins why for years I had the same problem in Windows... wanting to load drivers for a VGA I didn't want to use, but at least in Device Manager you could disable it.)
So thanks everybody for bearing with me and your support... again! I'll now mark the thread appropriately