OT: Repeating emails.

i have a hotmail account and using Window Live Mail 2011.  A group email I sent out keeps repeating to several of the receivers.  There's no coping of the resending email found in the sent box and there's on email stuck in the out box.  Some are getting up to 30 to 40 emails.  Very frustraing.  Not all of the receivers are having this issue.  

Any help would be appreciated