Are all lthose bits, taken from the installed 5000 loops of sounds or are there some others you added. Obviously, if the sounds are in those 5000 loops , then they will be there next time. The problem is knowing which exact sound was used in a mix. Saving just the project file will reopen a mix exactly as it was save last IF (BIG IF) there are no other sounds used except for those 5000 loop sounds.