I would recommend you run WEB MSN, this is a version that uses standard HTTP ports that your FW will allow no doubt. If that works, then a FW is blocking your traffic from MSN the applciation on a high end port. Finally, if you can do a System Restore to a date when MSN did work.
David Chances
February 2007
Are you sure that you only have 1 firewall on your PC? if you have installed any third party virus protection i.e norton or mcaffee you brobably have 2 firewalls running at the same time....turn 1 off.......