[Hummingbird] Hummingbird Page Cache crashes www

The last couple of updates to Hummingbird have caused major problems on my site. I use domain mapping on my WP MU site. All sites are redirected from www to non-www. However, after the last two updates, when someone browses to the www version, they received the following fatal php errors:

Warning: copy(/srv/users/knights/apps/knights/public/wp-content/advanced-cache.php): failed to open stream: Permission denied in /srv/users/knights/apps/knights/public/wp-content/plugins/wp-hummingbird/core/modules/class-module-page-cache.php on line 187

Warning: Cannot modify header information - headers already sent by (output started at /srv/users/knights/apps/knights/public/wp-content/plugins/wp-hummingbird/core/modules/class-module-page-cache.php:187) in /srv/users/knights/apps/knights/public/wp-includes/pluggable.php on line 1216

If they leave the www off, the site loads fine. This worked fine before, and works fine if I disable page caching.

I have enabled support access.

An example site is http://www.stcharleskoc.com. The weird thing is, this issue does not happen on my development site.

Any help would be appreciated. I would prefer to keep page caching active, but may be forced to disable it.