Guitar Hero 4 or Rockband 2?

My girlfriend got GH4 for PS3 and we were playing it at her place... Every so often, both guitars completely stop responding and just flash their LEDs over and over again. Popping the batteries out and back in fixes the problem, as does unplugging and plugging the wireless detectors from the console.

Anyone have any clue why it's doing this and how to fix it? It's not a low battery problem.