Thanks for the excellent advice Kevin, I've been waiting for the new board to reply.
There's been a bit of a breakthrough.
The bug wouldn't let me view certain sites, mainly one that would have helped me, updates etc.
Either it wouldn't let me onto a site where I could D/L a useful programme i.e. S&D, or, it would
let me D/L 'em but not let me online to register and initiate it.
What a clever bug........
I then went to FileHippo which let me D/L stuff without visiting their websites.
D/L Avast AV which not only ran from the start but does a scan prior to booting, which is some way towards what you were saying
about not running a check whilst PC is running.
It then let me load MalwareBytes etc which have continued the cleansing.
Not out of the woods yet but my PC booted normally for the first ever time in weeks.
Avast is a bit on the exciteable side, loads of hooters and klaxons like being on the bridge of the USS Seaview
but it's lovely to hear 'em
Bless you all for listening to the ramblings of a frightened man...