Thanks for the ideas. I tried the clean boot, after which the Maxtor manager stopped seeing the drive. I then tried testdisk, and the m/s site recc.s for testing a disk. Couldn't make test disk work,and the m/s stuff didn't help.
I've decided to go nuclear. Drive is now being formatted. At least it'll tell me whether or not I need a new drive.As it was back up no1, I guess I ought to fork out for a new external drive. (Back up no 2 still works).
thanks for the ideas.