Vista - why does live messenger log me back in after I've manually logged

For some strange reason, I've noticed that live messenger (version 2009) will
randomly log me back in after I've manually logged out. I do not want this,
because the only times I manually log out, are the times when I actually
don't want to be logged in. I try not to close msn, because it's much easier
just to right click the icon and tell it to sign in.

I like the automatic log in feature for when I lose my wireless connection,
or switch to another one, but I don't want it to use that feature to log me
in randomly after I've manually logged out. I want to have to manually log
back in before it comes into effect again.