WordPress 3.0 "don't have permission to access /index.php on this server" error

I currently update my blog to version 3.0, and edited the .htaccess file. My .htaccess look like this:

# BEGIN WordPress
<IfModule mod_rewrite.c>
# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

Now only my /blog work. The blog/sublog keep giving the “You don’t have permission to access /index.php on this server.” error

Any idea?
Thanks in advance.
Vicky