What does this error states in php?

Question

I have added htaccess file to my codeigniter folder and since then i get

Server error!

The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there was an error in a CGI script.

If you think this is a server error, please contact the webmaster. Error 500 localhost 05/20/10 13:16:23 Apache/2.2.8 (Win32) DAV/2 mod_ssl/2.2.8 OpenSSL/0.9.8g mod_autoindex_color PHP/5.2.5

My htaccess files has this,

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

Answer 1

it is not PHP error and it states, as Krab mentioned, "See web-server's error_log for the actual error message"

Answer 2

It's actually Apache error caused by your htaccess.

I think the invalid line is this:

RewriteCond $1 !^(index\.php|resources|robots\.txt)

The $1 is not defined there.