I have to admit I really do not remember chants being interrupted by the sound system. I say this because I rarely heard any chants to begin with that didn't somehow involve the Rangers, Flyers or Crosby.
I do think the song selection is lame and is getting worse every year. It seems that heavy metal is on a lot of fans wish lists that I've heard either on here, twitter, FB, etc. but I don't think it should be mostly that either. They really do need to get a better play list going.
It would happen if there was a big play before a TV timeout. There were more than a few times the crowd would be into it and then they would blast the music for the timeout rather than letting the crowd cheer. Not something that happened every game necessarily but it did happen.