Loud Pop, then No Sound in PTLE

hey guys, i'm having a weird PTLE problem. it happened on my old version of pro tools, so i reinstalled, and i'm still having the same problem. i'll try my best to describe it. it started doing it only on one session, and has now increased to two sessions. i'll go to 'open' to open the aforementioned session. as it is loading, i hear a loud pop through my monitors (im guessing around 100hz) just as the session is about the finish loading/launch. then i get into the session, and there is no sound. all of the meters work on all of the tracks, showing that there is level, but there is no sound. when i click to 'solo' a track, it will play the audio from just that track. then i 'un-solo' it, and again, no sound. i can solo up to about 4-5 tracks in the session at a time and get all the audio playing from those select tracks, but if i go above a certain number, once again, no sound. when i close the session, i once again hear the loud 'pop'. this is a really weird problem to me. i've tried a few different things. i've tried to save a copy of the session and re-open the copy - this worked the first time i did it, but has not worked since. even a fresh install of pro tools did not fix the problem. please help!! thanks!

EDIT: make that THREE sessions. i was in the middle of working on one just now and low and behold, i added 4 new mono audio tracks to the session. as soon as i pushed enter, i heard the pop, the tracks were added, and there was no sound. three sessions and counting.. ..please help

I have the same problem. anyone please!