This is driving me nuts.

Background: I'm using the built-in Apache2 & PHP that comes with Mac OS X 10.6

I have a vhost setup as follows:

NameVirtualHost *:81

<Directory "/Users/neezer/Sites/">
    Options Indexes MultiViews
    AllowOverride None
    Order allow,deny
    Allow from all
</Directory>

<VirtualHost *:81>
    ServerName lobster.dev
    ServerAlias *.lobster.dev
    DocumentRoot /Users/neezer/Sites/lobster/www

    RewriteEngine On
    RewriteCond $1 !^(index\.php|resources|robots\.txt)
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php/$1 [L,QSA]

    LogLevel debug
    ErrorLog /private/var/log/apache2/lobster_error
</VirtualHost>

This is in /private/etc/apache2/users/neezer.conf.

My code in the lobster project is PHP with the CodeIgniter framework. Trying to load http://lobster.dev:81/ gives me:

400 Bad Request

Normally, I'd go check my logs to see what caused it, yet my logs are empty! I looked in both /private/var/log/apache2/error_log and /private/var/log/apache2/lobster_error, and neither records ANY message relating to the 400. I have LogLevel set to debug in /private/etc/apache2/http.conf.

Removing the rewrite rules gets rid of the error, but these same rules work on my MAMP host. I've double-checked and rewrite_module is loaded in my default Apache installation. My http.conf can be found here: https://gist.github.com/1057091

What gives? Let me know if you need any additional info.

NOTE: I do NOT want to add the rewrite rules to .htaccess in the project directory (it's checked into a git repo and I don't want to touch it).