No automatic log in on Windows Messenger startup?

I'm trying to set up my mother's computer so that Windows
Messenger automatically starts up and logs her in when
she boots, to facilite her getting 'remote assistance'
from me.

Both she and I are using Win XP and have Windows
Messenger 4.7 loaded. We both have active accounts and
passwords with Windows Messenger.

However, on both her computer and mine, setting the
options under 'preferences' to "Run the program when
Windows starts", the Messenger main window appears on
startup, but we are not automatically logged in. (Note:
we can "click here to sign in", and everything works
properly.)

Clicking "To sign in with a different account, click
here." pops up the .net messenger service dialog box,
where we can enter our passwords and (re)check the box
that says "Sign me in automatically", but after we log
off and back on, the password is cleared as well as the
checkbox.

I note that if we also check the option "Allow this
program to run in the background" in Preferences, there
is no evidence that the program is run automatically at
startup (no icon in tray, no window appearing on boot up,
etc.).

A search on "automatic log in" reveals an entry "Stop
Windows Messenger from signing you in automatically", but
nothing that explains how to turn this feature on!

Please help! Any advice appreciated!





Can someone please explain what's