Auto Sign-on Problem

I have two PCs at home both running Windows XP Pro and Windows Live Messenger
8.1. At boot time one PC works flawlessly and starts Windows Live Messenger
automatically. Despite the settings being identical, the second PC does NOT
load Windows Live Messenger automatically. While the second PC can be signed
in manually without a problem, this is a nuisance. I’ve been all over
looking for a reason for this anomaly but so far nada. I’ve checked and
rechecked the settings, looked in the Registry as well as in the Event Viewer
for clues without success. Any help and advice would certainly be
appreciated!

Thanks,
DickK