Internal Server Error on Multisite Installation

Am having a bit of trouble with a site that was installed onto the server as lizziesloan.com/wp instead of into the root directory as lizziesloan.com

I have moved the files to the root directory, but am now having some issues getting the site to work properly ..

The wp-config.php file has the following …

define('WP_ALLOW_MULTISITE', true);
    define( 'MULTISITE', true );
    define( 'SUBDOMAIN_INSTALL', false );
    $base = '/wp/';
    define( 'DOMAIN_CURRENT_SITE', 'lizziesloan.com' );
    define( 'PATH_CURRENT_SITE', '/wp/' );
    define( 'SITE_ID_CURRENT_SITE', 1 );
    define( 'BLOG_ID_CURRENT_SITE', 1 );

When I try to access the site, I am able to view the home page, but I cannot login to the dashboard and when I try to access any other pages from the homepage navigation I get the following error …

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@lizziesloan.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

If I change the wp-config file to

define('WP_ALLOW_MULTISITE', true);
    define( 'MULTISITE', true );
    define( 'SUBDOMAIN_INSTALL', false );
    $base = '/';
    define( 'DOMAIN_CURRENT_SITE', 'lizziesloan.com' );
    define( 'PATH_CURRENT_SITE', '/' );
    define( 'SITE_ID_CURRENT_SITE', 1 );
    define( 'BLOG_ID_CURRENT_SITE', 1 );

I am no longer able to access the site at all …

Obviously I am missing something …. !!

Would really appreciate it if someone can point me in the right direction to fix this.

Thanks
Meg