Media Library and pics in WPMU doesn't work

Hi to all, i hope you can help me because i’m going crazy 🙂

I wanted to have a site translated into 3 languages (including flash movies and pics) so I installed WP 3.0.1 in network mode, with subfolders. So now I find a main WP installation that controll other 3 sub-sites.

In main WP everything works perfectly, and the pics seems to work properly, and stored them in wp-content/uploads. If i load same pics by the secondary WP installations, the images are loads, but i can’t see them.

The pictures are loads but doesn’t appear in Media preview panel, and if I recall the pics in a page or an article, I see the small image corrupt icon.

I thought it was a problem with .htaccess file but it seems good.This is my .htaccess file:

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

I think that this file is accurate…

So,I thought it was a problem whit folders permissions. I check the folders and i check this path: wp-content/blogs.dir/2/files…. all theese folder have the 0777 permissions.

Now, i don’t know if there are permalinks problems, or something else… i did other tests:
I uploaded the pictures with the media library, via ftp and through other plugins… I installed the default plugin twentyten and I removed all plugins, to see if there was any incompatibility… but nothing… there is always the same problem…

I hope u can help me… I do not know what to do

Sorry for my bad english
greetings
Niko