I had problems getting lynx to quit at one time.
My solution was to have the cron call php directly. For example:
30 15 * /path/to/php /path/to/routine.php
or, specifically in of my cases,
22,52 /usr/local/bin/php -q /home/sites/home/web/images/temp/cron_delete_files.php > /dev/null
Hope that helps.
Rob