Multiple Downloads of Mail

I am using Live Mail 2012 with Windows 8.1 (64 bit).  My ISP is Comcast.  I have my Live Mail account (only one account) set up to leave messages on the Comcast server for one day.  Messages are downloading normally unless, for some reason, I lose my internet connection or I shut down Live Mail.  In that case, when Live Mail starts up again, it downloads all the messages again.  This didn't happen when I was using Live Mail with Windows 7.  Somehow, it doesn't remember that it's already fetched the messages.  And sometimes, when it fetches them again, they come through with the message "The content of this message cannot be found".  Any suggestions?