it sounds like a possible server config issue. Couple of things to try with your host:
1. Check with your host to ensure the .htaccess file is installed.
2. Get them to increase the PHP Memory Limit, its currently at 40meg, i would recommend at least 256meg or higher. Once they increase that you need to edit your wp-config.php file and look for this line:
define( 'WP_MEMORY_LIMIT', '40M' ); and increase this.