I was having trouble chasing down bugs after modifying a couple of nodes. After hours of chasing my tail I figured out that nodes that aren't connected to the Start node might still be executed. I was making duplicates of nodes and connecting one of them to the Start node and figuring that was the only one being executed. That's not necessarily the case, which I understand now can be a benefit as long as you know that's the case. I do not know what the rules are regarding which do and which do not get executed, but I suggest you have no extra nodes that you aren't using in the nodes window of the object your're working on.