It's gone back to PB Tech (I have nothing but praise for them so far over many years - hopefully this will be the same).
Following steps ouline by GZT - I had tried before but didn't work - just went straight to start installing - didn't get a repair option. Weird I know I had tried thinking there would be one that way - but not so.
F11 didn't do anything.
I was going to re-install on drive C - but it wouldn't let me - some weird letters instead of some other weird letters. Can you tell I'm exhausted - recovering from a virus and battling this for nearly four days is too much Didn't even lookup what the error message meant.
So now all I have to do is figure why some accounting apps won't install on my old machine, and hope no-one wants help before they fix it (and I reinstall the many programs on there).