Try this (FreeBSD. The path on Linux boxes may vary):
Enable the cron check in admin and use a password if desired (NOT YOUR ADMIN PASSWORD). Then, to run at midnight every Sunday:
Code:
0 0 * * 0 /usr/local/bin/wget -q --delete-after http://domain.com/linkex/?page=check&passphrase=password (if you chose to use one) > /dev/null