New Digg Digg error preventing the whole page from being displayed

Hi,
I’m running Digg Digg 5.2.9 and WordPress 3.4.2, hosted at WPEngine.
I’m running into this error:
[Tue Sep 25 08:59:37 2012] [error] [client 89.238.233.38] PHP Fatal error: constructFloatingButtons() [function.constructfloatingbuttons]: The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "DD_DZone" of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition in /nas/wp/www/cluster-1266/baeldung/wp-content/plugins/digg-digg/digg-digg.php on line 288, referer: http://baeldung.wpengine.com/wp-admin/post.php?post=1588&action=edit&message=10

This leads to the entire page simply remaining blank.
First, does anyone have any idea why the plugin is not sandboxed so that, when it does fail, it still allows the rendering of the page, instead of resulting into this kind of severe error, where nothing is displayed?
Second, I see that this kind of error was reported before with Digg Digg, and that it may be related to caching; WPEngine does it’s own Caching and CDN, is there any way to address this limitation and restore functionality?
Thanks.
Eugen.