How can I troubleshoot this error in my log.

5/17/2015 1:30:47 AM: Error in activateSceneByGuid:Object reference not set to an instance of an object. - System.NullReferenceException
Object reference not set to an instance of an object.

at MLS.HA.DeviceController.Common.HaControllerInterface.DeviceManager.<>cDisplayClass6a.b65() in z:\work\mls\MLS.ZWave.Controller\MLS.HA.DeviceController\DeviceManager.cs:line 1410

I think I got this error when I activated a scene that turns off a bunch of outside lights except for two when I go to bed. That scene ran REALLY SLOW when I clicked it at about 1:30 this morning. I didn't feel like staying up to troubleshoot it at the time.

Thanks

N0VTN