Vista - Windows Live Messenger will not start on Windows XP SP2

I had Windows Live Messenger v8.5 installed and running on one of my
desktops. It has been running fine up until last week. It was working the
weekend before. Last week when I would try and start it, it would open up
and just hang, not even allowing me to login. The only updates that have
made to the PC have been the one released from Microsoft and the McAfee virus
updates. This PC is not used that often so I do not believe it is related to
something that was done. After repeated reboots I decided to uninstall and
reinstall it from the PC. After uninstalling the application I rebooted and
went online to download and redo the installation. Once it was reinstalled
and I logged in and experienced that same problem, where it would just stop
responding and hangup. This seems to only be effecting the installation on
this one PC. I have another PC and a laptop on the same LAN and I am able to
get it to work on them without any problems. What else do I need to do to
correct this problem on this PC. Is there a registry setting or file missing
that might be causing it to hang up.