I think you can't change it back. You've installed Windows XP SP2 which has got an updated Windows Messenger which opens Outlook instead of IE to check your Hotmail.
Windows Messenger and Hotmail email - by misteranswer on 10-24-2004 at 11:12 AM RE: Windows Messenger and Hotmail email - by Kryptonate on 10-24-2004 at 11:43 AM