Protected Content Causing error with another plugin


We have recently added Protected Content to use on one of our sites in an MU installation. When we Network Activate the Protected Content plugin, we have noticed that we can not save changes to the ever-popular LayerSlider plugin. The saving freezes. The error in the js console is: Uncaught TypeError: Cannot read property 'substr' of undefined, and indicates an issue with a custom .js mod. When I Network Deactivate the plugin and reload the LS admin page, I can save just fine, no error. If I Activate PC again, I get the error. I very cleanly troubleshot several times to make sure the series of events and error held true. I also noticed that when Protected Content is activated, there are several custom .js libs from Protected Content. Not sure which one might be the factor.

Thanks for your help.