I didn't notice there was an update and was using version 1.6.2 previously.
I have updated to version 2.0 today and now these server errors are showing up:
Server Error Log Error Info
ErrorException: Fatal Error: Class 'RotatingAds_Engine' not found - library/RotatingAds/Listener.php:18
Generated By: Unknown Account, A moment ago Stack Trace
#0 [internal function]: XenForo_Application::handleFatalError()