OK - many thanks to kimsland and Peddant for assistance.
I seem to have finally cracked it by typing chkntfs /x c:
I saw this at the bottom of the screen in "Similar Threads" A question raised by cfitzarl on 31 Aug 2006 was answered by Peddant. I wonder, however, if this route has disabled Check Disk as in CCT's kellys-korner?
Once again, Thanks to all
JJM