Windows Live Mail Contact List Query

I was using Windows Live Mail (2012) on my old computer and an older version of Windows to sent out lots of information for my netball club.  I had categorised contacts into categories.  I purchased an Asus computer which runs the latest version of Windows.  Since setting up my new computer with all the contact categories, I am finding that when I go to send something to a category that they are gone.  All my contacts are still in the mail list and the category is showing the number of contacts in brackets when I go to check, but when on click on 'edit category' there is nothing there and I have to save them all over again.  I resave them all and it might last for a few days to a week or more and then suddenly they are all gone again and I have to resave the categories.  Having 40 categories which are used on a weekly basis, this is becoming very annoying.  Any suggestions?????