Messenger Update Problem

Archived from groups: microsoft.public.windowsxp.messenger (More info?)

Every time I reboot my computer, I get an error message saying that a newer
version of Messenger exists that I must install before proceeding. Then when
I try to do that, it says that I must close all other programs before
proceeding. The only problem is that all other programs are closed! I've
tried disabling McAfee antivirus and that does not work. I looked in the Task
Manager under Processes and I see that a zillion processes are running, but I
don't know which is the offending one to disable in order to proceed. Anyone
have any suggestions on solving this problem?
Thanks,
Hal