Conan
Thank you for the suggestions. I haven't, so far, e-mailed San Disk, mainly because the card is useable as a transfer device but no use in the cameras.
I DID try the reformat option but only as FAT and FAT 32 because the NTFS option wasn't listed. On the one reader that works, it was fine, but, as before, the card was unreadable on any other reader or the cameras.
I have also tried transferring the DCIM plus sub-folder info onto the card and then trying in the camera but, again, no joy.
I have to say that I cannot see why a collection of 0s and 1s can so drastically change when looked at in different devices. Digital is very strange
