Dear Old Polack
Thanks for helping. As it was the partition being "screwed" and the obscure numbering thereof was a red herring. This should have been evidenced by the no-problem installations of other linuxi and other OS's and the use of a non-screwd partition disk.
However poking around did give me a clue which should have been obvious to me in hindsight. On an abortive manual boot from grub I saw a message saying it was ignoring raid hardware this prompted me to recall that although vista installed no problem, XP and 7 barfed

. That is because there is some strange hardware on the machine and you must load a driver before windows install.
I can only surmise that some OS's do a deeper hardware analysis/whatever than others. In the case of PCLOS it neither asked and neither did I have such a driver. Evidently I therefore cannot "install" on that machine, although it can "run" thereupon

So I moved my efforts to another machine which I should have done ages ago. Persistance can be a handicap at times, probably most times. Lo and behold it installed perfectly but as that is a latest machine various hardwares went unrecognized.
I then transported said hard disk back to the errant machine and with a brief interruption where it noted my graphic setup had changed I was back in business

So thank you to everyone I annoyed and bothered. I think I have a Linux that is quite exploitable with internet and Lan connection

Kudos to the PCLOS guys for the easy (if somewhat problematic) hardware support. Mayhaps one day I can be MS free.