(Sorry if this is the wrong forum...given that I don't know what's causing the problem I don't know which forum is most appropriate.)

My sister is experiencing trouble with outgoing email using Outlook. In the past two days I've started receiving emails from her intended for others. Apparently two other contacts of hers are also receiving emails she's sent to others. Don't know if its random or consistent, and she doesn't seem sure herself.

In addition to the unintended recipient issue, her email information in my inbox has had an unusual change. I use Yahoo Mail and her incoming mails in the past showed her name, properly, as the sender. In my inbox view it would simply say her name (Sally McCutcheon), and when viewing the message it would say, again properly, "Sally McCutcheon <sally@blah.net>" (actual name and address changed for this post, of course).

Now, in my inbox view it says, "eonSally McCutcheon," and the "eon" prefix is there when I view the message itself as well. Seems that whatever is causing this issue is grabbing the last three letters of her name and sticking them at the beginning.

Anyway, given her lack of computer experience getting more details is difficult. Do these two symptoms indicate a specific problem anyone is aware of, and, if so, how do I instruct her to deal with it? She uses McAfee and says that nothing turns up when she runs a scan. Thanks in advance to anyone who can help.

Try working through the MRP:

http://wiki.castlecops.com/Malware_Removal_and_Prevention:_Overview