Stopping Messenger .Net Auto Signon

I need some help here, this is driving me mental

I setup my Mom's PC the other day and when i installed
messenger, it asked me if i wanted to use it to signin
to .net services when windows starts. Stupid me says Sure
go ahead.

Here is my problem

When i boot windows, the default profile that loads is my
mom's. MSN messenger is not loaded in my systray nor am i
logged into it. I told it to NOT start when windows loads.
However, i am still getting messenger messages from
people. So when im not on the PC and my mom is, she is
getting all sorts of people trying to msg me.

If i load Messenger, it starts but im not signed in until
i tell it to yet im showing online to my contacts and they
can message me.

I check my services and there is msmgs (not sure exact
spelling, im at work) that is loaded. If i terminate the
service and launch a web browser, that service starts up
again and i am getting messages from my contacts.

Anyone know how the hell i can disable this so that
Messenger .Net signin ONLY happens when i choose to load
MSN messenger myself.