MSN and Outlook conflict

I have a situation where an executive of my company is running Outlook 2003 along with MSN. When in Internet Explorer, or Windows Explorer, and trying to use the ‘Send to’ function to e-mail a file, it invokes MSN instead of Outlook. All default E-mail settings in IE are pointing to Outlook. All the office programs, and Adobe Acrobat will function perfectly with the ‘send to’ function, but Internet Explorer and Windows Explorer dont, even if Outlook is already open.
Any ideas would be greatly appreciated. Thanks a lot!