Thanks a lot! I read the article, and try to upload other .ico files (I am pretty they are correct .ico files). The problem still exists.
I think I will modify the code directly
<link rel="shortcut icon" href="xxxxxxxxx.ico" type="image/x-icon">
or add the code
COPY CODE
<location path="favicon.ico">
<system.web>
<authorization>
<allow users="*" />
</authorization>
</system.web>
</location>
where and how could I modify the <head> part.
Thanks a lot!