I have restored the bulk of my missing links as per your advice. I note the links that I validated prior to my build were lost, but better that then the entire list. For the record I made no changes as per your queries below.
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"Have you made any changes to your links.def file? The problem is with calculating the Ratings of Links in your database.

Have you inadvertantly deleted the Rating field or deleted $db_ratings in the IMPORTANT field section in links.def???"

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Quite simply as described earlier the build I attempted returned the error message as stated earlier. A subsequent build did show as successful but approx 80 links just vanished. It would be nice to know what happened so I don't live in fear of a recurrence. Any room here for blaming the web hosting service??

Thanks again for the quick response, it is appreciated!

Stevo