Sound tracks STILL spontaenously inaudible-BMD pls help!

I thought I had my audio failure at least[b] partially figured out, but no. [/b]
1) Will not play through computer speakers as before.
2) Set preferences to go through USB interface into monitors and worked... for a time.
3) Opened DR17.2 Studio this morning to continue editing project... no sound.
4) Checked preferences. Still set to MOTU M4 (USB interface) but no sound.
Edit: After I typed this initial help request, I went back to DR17.2 and hit the space bar again to see footage before closing the program and there was sound through my monitor once again. I had sat here for 5 minutes trying to figure things out before going to the forum and probably another 5 minutes typing up this request for help thread. WHAT IS GOING ON?????
I AM STUCK AND THIS IS REALLY FRUSTRATING. WHAT IS GOING ON HERE AND HOW DO I FIX IT????
1) Will not play through computer speakers as before.
2) Set preferences to go through USB interface into monitors and worked... for a time.
3) Opened DR17.2 Studio this morning to continue editing project... no sound.
4) Checked preferences. Still set to MOTU M4 (USB interface) but no sound.
Edit: After I typed this initial help request, I went back to DR17.2 and hit the space bar again to see footage before closing the program and there was sound through my monitor once again. I had sat here for 5 minutes trying to figure things out before going to the forum and probably another 5 minutes typing up this request for help thread. WHAT IS GOING ON?????
I AM STUCK AND THIS IS REALLY FRUSTRATING. WHAT IS GOING ON HERE AND HOW DO I FIX IT????