Explorer won't reconized files in some directory

[Belaran]

here is the problem:

apache is running and php4 too.

i can access my .php file and .html file in
http:/127.0.0.1/~username/ without any problem.
but when i try to go to a folder inside site , i get this :

Forbidden
You don't have permission to access /~belaran/CD_Romain/index.html on this server.

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Apache/1.3.27 Server at belaran.local Port 80

What's the XXXX is wrong with my system ???