Richard,
Thanks for the lead, I'll look into it over the weekend when I have time to let my email system be immobilized. The problem of contacts being deleted is by no means unique to me. There are many, many posts about this on the Window Live Mail support site.
My problem, however, doesn't involve the deletions. It involves the fact that the backup software supplied with Windows 7 Professional edition cannot restore the contacts file when it is deleted. The issue is not one of not actually backing up the file. The Microsoft Jocks and I established that they were backed up properly. It is apparently a flaw in one of the programs. But Windows Live Mail doesn't have live support people -- even on a per fee basis -- so there's no one to ask about this. Frankly, I'm sorry I used this software at this point.