My Tracks keep going after the track should end, How can I tell it to stop at the end of the song

How to place a stop command on a track?

SONAR always plays through the last bit of data. There is no "stop command" which may be added to a track or project. Assuming there is nothing past the expected stopping point, enable "Stop at Project End" in the Track View Options menu. This will cause SONAR to stop when the last bit of data is processed, otherwise; the transport continues to run past the last bit of data.

Thanks Snook, I appreciate your quick knowledge response
 
 

One thing that's confused me after checking the above stop-at-end flag mentioned above is when it STILL goes past the apparent end of the longest clip. Invariably it turns out there is an extended automation envelope somewhere that is the culprit there.

I had that symptom and did ctrl end. Viola! An errant note in measure 480. How it got there, I have no idea.

You can use a Doepfer MCV4 MIDI-CV/Gate.
So a simple MIDI information on a midi-track can switch the power socket from your computer. This stops SONAR.