hmmm....
Well maybe, like on the old one, when a lot of zombies break into the house the music flares because it thinks you will die... Maybe its the same this time? I never hear it bcoz of the constant roar of brownings and ray guns, but maybe if I cranked the volume I'd have it to?
Also with the toilet thing try flushing the same toilet 3 times, let the sound completely finish before flushing it again. Then the song you heard with the 'give up and die' should play. (Its called lullay for a dead man, if you didnt know

)
Erm theres a couple vids on youtube about the toilet thing... Il find ya one if your sure your toilets do nothing?
Not sure what else to suggest