Uploaded images not appearing

I see a lot of others are having this problem too, but I cannot find a solution that works for me. I have rebuilt my .htaccess and config.php files, and still I only have a framed white space where the images should be embedded. I suspect that this is a rewrite problem, and not an issue with my server.

The contents of my .htaccess file are as follows (it is taken from my Dashboard > Tools > Network settings):

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

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule . index.php [L]

I am looking for any suggestions on where to go from here. Should I reinstall WP3.0?

Thanks so much,
Courtney