The following snippet is from the 50 Hz Kicker JSFX that comes with Reaper.
Code:
gain = min(max(env2/env1,1)-1,1) * wet;
The thing here is that if Reaper is stopped and nothing is playing through the JSFX, both env1 and env2 become zero. And the strange thing is that if Reaper is not playing for close to 4 minutes, the 50 Hz Kicker starts emitting a sine wave of the set frequency at the gain set by the "wet" variable.
I can only assume that this is because the divide by zero inside the max somehow makes the whole max-min expression suddenly return 1, so that gain is set to the value of wet.
But if this assumption is correct, that behavior seems very strange. I understand that divide by zero is undefined, but still... I would expect some consistent behavior.