500 Internal Errors off root

Hi,

Developed a site for a domain called xyz.com and installed wordpress on the shared hosting I have in a sub directory called blog. Everything was working fine.

Hosting lets me change where xyz.com and http://www.xyz.com can point to, so I changed it from xyz.com pointing to htdocs, to the sub directory, and added

define(‘WP_HOME’,’http://xyz.com’);
define(‘WP_SITEURL’,’http://xyz.com’);

to wp-config.php so xyz loads the site found in the subdirectory..

No when I load the site , all text, images, css and media load fine off the home page but anything off it has an internal 500 error..interestingly in phpmyadmin, the site url in the database is still set to xyz.com/subdirectory. Could this be the problem

Thanks..