I don't know what's the problem with my project but regularly (not all the time) midi channel 2's volume resets to 0 when I start the song.
When this happens I need to roll the "modulation" wheel of my keyboard controller (don't ask me why) in order to adjust the channel 2's volume back to normal. My track #2 holds a midi sequence that has all notes played on the channel 2.
No other track or channel has this problem.
Did this situation happen to any of you, and knows why does this happens and knows how to fix it?
 
Here is my setup:
- Sonar Artist, M-Audio keyboard (Oxygen49-blue).
- The 4 midi tracks' output are directed to a VTS instrument (Miroslav Philarmonik).
- The VST plugin has 16 possible outputs, each having a dedicated instrument track.
- So the 16 instrument tracks' input are set the the corresponding output channel on the VST plugin.
- The 16 instrument tracks' output are set to Master.

I'd start by taking a look at the MIDI track in the event viewer to see if there are any unwanted MIDI CC entries in there that might explain things. Particularly CC7 (volume).

Or maybe mod wheel data at the beginning of the track that might account for the volume loss, such as lowering a low pass filter's frequency to below the frequency of the notes.

Another possibility is the "zero controllers at start" setting in preferences. Whichever it is set to (on or off) try the other.

Thanks for you reply. I checked my midi tracks with the midi event list and could not see anything else than Note events. Still, I disabled the "zero controllers at start" option and for the moment I could not reproduce the problem. I'll leave like this for a while and see if it the problem disappears.