rewrite rule

I have a weird problem. I am using a multi-site installation. I inherited the setup and while I think the problem is in the setup, I am perplexed. The .htaccess file has 4 sites in the form:

RewriteCond %{SERVER_NAME} ^mysite.mysite1.domain.com$ [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !=/favicon.ico
RewriteRule ^(.*)$ http://mysite.mysite1.domain.com/index.php?q=$1 [P,L,QSA]

I am using Virtual hosts and that conf is:

ServerName mysite.mysite1.domain.com