IIS Auth Client two time when click on xls Link

Hi All,

Using IIS5.0 and Office2003+ open a excel link, I got two times authentication. Is it work as usual?

(I have got to the follow link, and deploy registry solution:

http://support.microsoft.com/kb/2123563/en-us )

I tried deploying SSL Solution with baisc authentication, it still process two time auth. 

(http://www.authenticationtutorial.com/tutorial/)

May i know how to avoid two time authentication except no security. thanks

Rgds

Andrewlpchan