Having trouble running that cron.php in Drupal? Receiving a 403 error? Here's where to look...
In the .htaccess file in the root of the directory there is a section near the base that looks like:-
Deny from all
Allow from localhost
Allow from 127.0.0.1
Allow from xx.xx.xx.xx #<= YOUR IP
Use a service like WhatIsMyIP to find out your IP address, replace the xx.xx.xx.xx with your IP and voila, you can call cron.php from the browser.
Bear in mind if you reboot your router or are assigned another IP address you will need to change this value if accessing from your browser again.