Are you using this plugin?
Also, I've dealt with CiviCRM before with WP. There are several issues with it that crop up from time to time.
From my experience, often when errors are thrown by the system, they point to PageLines Framework, but in fact, the errors have nothing to do with the Framework itself. It's just that it happens within the view of the Framework, so the error is displayed that way.
From the looks of that error, my guess is that the cronjob should in this case, be outside the WP structure, since it's calling upon the server's mail function, not a WP function. To support this, read this Drupal related article:
as it describes the need to put the cron in the server root.
CiviCRM should provide you with support for setting up a cronjob for mail and I believe this topic may point you in the correct direction:
This Wiki from their site may also help:
Unfortunately, this cron task is something that should be supported directly by CiviCRM as PageLines isn't going to block any cron task set up properly outside the parameters of WordPress.
Hope this helps!