[TYPO3-windows] "Page not found" problem on IIS6

[Fred]

Hi,
I have a weird problem with my website.
I tried to install Typo3 on www.mysite.org but I only obtained a "Page 
not found" with the "typo3/install/index.php?mod=123?name=joh316..." 
adress (I don't have all in head).
So I tried to found out why and I discovered this strange bug :
When I use http://www.mysite.org adress there is no problem, but if I 
use http://www.mysite.org/index.html I have the 404 error (/whereas I 
actually have a index.html in my root folder !/). I put a little 
"test.txt" file on the same folder and I tried to read it with 
http://www.mysite.org/test.txt ... no problem to read it.

I tried to compare this website with my olders but I didn't found anything.

Does anyone have a clue ?

Thanks a lot !