I figured it out. I had to modify my hot linking options in CPanel.
Go into your site’s CPanel and either enable hotlinking or add http://www.pinterest.com to your allowable sites. It immediately rectifies the issue.
This thread explains a work-around. I tried it & it sets things back to ‘normal’. Looking forward to an actual fix.
http://wordpress.org/support/topic/error-in-pagephp-in-new-release-13?replies=7
I figured it out – my default media sizes changed & altered the theme.
