Contacts Disappear from Windows Live Mail in Windows 7

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I have been using Windows 7 and Windows Live Mail without trouble for 2 years. Now I am setting up a new desktop computer for my spouse. It also uses Win7. I downloaded/installed WinLiveEssentials then set up her existing email account with no problem. I imported addresses from Outlook Express 6 using the *.wab file. It imported all addresses and groups (categories) without problem but within a few hours, half of them disappeared. By the next day, they were all gone. I imported from the wab file again but now only half of them go in and, after awhile, they disappear also. There was no MS update during this time. In looking at the file structure, I found the contacts.edb files in hidden system files in Users/Username/AppData and so forth. When the contacts have disappeared, contacts.edb files are gone and the DBStore folders are empty (with hidden files revealed). I have not set up a Microsoft Account for her and so have not 'signed in'
The WLM version is 2012 Build 16.43505.0912
Loss of Contacts in Live Mail seems to be a common problem but I've seen no reliable 'fix' yet. I hope someone can help! Thank you