The previously installed 1 TB HDD (which had worked OK for years) became faulty so was replaced with a 1TB WD 10sPCX-08M. I had on hand. It checked out fine on this PC.
This internally mounted HDD is recoignised but fails to completely initialise.
About all my exhaustive searches can find is that maybe WD drives have this problem. I've ordered another 2Tb Seagate ST2000LM007 7mm 2.5" internal SATA 6Gb/s 128Mb laptop Hard Drive and hope this will solve the problem but am posting in case there is something else I should know about and do.
Help most appreciate thanks