Problem solved (I think). It would seem as though two things might have been to blame, possibly three.
The MMC was locked in correctly, and after a little coaxing now appears okay.
The camera (somehow) had been reset, and required re-setting!.
The person owning the camera, not sure what he was doing :O(
Anyway, all's well that end well. So will close this.
Unless someone wants to add anything further, especially on the uprated from 64MB to 256MB, and if this will improve issue. Plus does use or know of any issues with DataSafe MMC's?.