Error while looking MIME type for JPEG image file in Netscape

Error while looking MIME type for JPEG image file :

Reson:

Internet Explorer treats all jpegs as type=>image/pjpeg
Netscape/Internet Explorertreats all jpegs as type=>image/pjpeg

where as

Netscape/Firefox treats all jpegs as type=>image/jpeg

What genius at microsoft decided to rename the mime type for jpgs?