multiple emails

Good morning- I hope someone can answer this: last night I received 10 copies of an email from a friend-(it was a reply to my email to her). There was no text in the text area, although she said she had written something. Below that was a warning from my Avast program- all it said was "incomplete message warning". This friend has had something going on for months where her computer sends multiple copies. She is fairly computer illiterate, and pretty naive. Has she picked up a trojan, virus, or what could be going on? She has McAfee, which is about to expire, and she thinks she has to pay big bucks for protection. I told her the free Avast takes good care of me. Could Facebook have anything to do with the problem? Any help will be appreciated. Thanks- Jo in WA