You're the man! This tweak helped me get audio working on a Dell Dementia 4700, running JaS 10.4.8 installation. Unfortunately, the built-in Intel Pro/100 VE fast ethernet is still a mystery despite all the useful tweaking info around for it.
Does your current machine have QE/CI working?
Did your previous, stable machine/installation have QE/CI working?
Do others reading this have Safari running smoothly (and is your QE/CI working)?
Are you a fan of the Socratic method yet?