I've been on the receiving end of some of those strange emails from contacts who use hotmail. (I use gmail) The only way I've found to stop them is delete that contact and re-establish them.
Sorry I can't help with how to fix it from your end, other than stop using hotmail.
Recent update is I had to change my password in hotmail, all done there.
I also have to change my password for my router, will get my isp to sort this out tomorrow, so far the change of password for hotmail seems to have done the trick.