Thanks for the response, but I'm not sure if I completely understand your answer. We do both sign in at different times normally to check our respective mail. For 2 months....no problems. Then suddenly for 2-3 days our contact lists were going crazy. I'd look at mine and have some of her contacts and also several were duplicated. I'd fix it, and the next day it would be messed up again, but differently. The same thing was happening with hers.
I repaired them again last night, so I'll see what happens. We always close out our email sessions when finished.
I'll check on the site that you mentioned to see what's there.