I have set up various groups/categories in Windows Live Mail for sending group e-mails and when I click on them, they appear to have everyone in, but if I try to send an e-mail, there are either no contacts in there or there is only partial recipient addresses in there. When I click on the category to edit it, the original contacts have all disappeared or partially disappeared! I try putting them in again and click save and they don't stay there!  It used to work fine, what is happening??    

I have personally spent 4-5 hours  and tech support has spent an additional 5-6 hours, no error message. Tried online repair, etc. Tech guy said another customer has same problem.