msimn.exe (task manager), is MicroSoft Internet Mail and News, the executable running your email program, probably Outlook Express?
Although you may as you say have sorted the 127.0.0.1 thing, you may not have resolved everything.
Check out the Avast Help file @ Windows 'Start' (buton)> All Programs > Avast > Help. Since you have been manually adjusting the email setings, check out the 'Setting up the Mail Protection' and the 'Manual setting of mail protection' section in particular. Here you can confirm if, what you have done is it correct, if there more to do, etc.
Unfortunately you don't give us much to work with in your post, a copy of the error message would I'm sure be helpful to those more knowledgable than I in these things.
HTH - David