As far as I know, this effects every version of Ableton up until the current version of 5.0.1. The problem is that upon hitting the stop button, only a note off message is sent to in-use midi channels, where the behavior should be to send an "all controllers off" message as well. Why? Say you are using a sustain pedal, and have recorded a track where the pedal is held for a couple of measures. If you hit stop at a point where the pedal is recorded as being held, the notes being played at that time will hold indefinitly. You can then press the pedal, which will stop the note(s) from holding. Having to do that can get extremely annoying.
I was able to find a post that also identified this as a problem. It ended with an Ableton employee stating that it would be fixed; but it hasn't.
This seems like a pretty big bug, so I could be missing something; let me know if that is the case!
Ryan