Media files opening in outlook express

Stresssss again!! I am having problems opening windows media files. They attempt to open in Outlook express. They have a .asf file extension. Bur when I try to open and play it oe puts a .dbx file extension on it. I am using Netscape mail .Also When I tried to down load an updated version of my windows media player from microsoft it downloaded with a oe file ending and won't open it simply brings up outlook express. It seems that they both have a .dbx file extension.
Can't figure it out!
I am running win 98 os