Hi Jan,
Today I lost the audio in my intel iMac system which I have used reliably for a couple of years to record audio files. I have an external sound card, monitors..essentially a pro level studio here in Tokyo. Searching for possible problems, I came across the "iTunes Helper(not responding)" message in Activity Monitor. Searching on-line I located your answer, it seemed reliable so I followed it. In Start-up Items, I didn't have iTunes Helper listed. So,
I located the file, dragged it into Start-up Items, restarted and checked my audio. Nothing. So I checked System Sound...it worked. I did a Disc Repair, drank halfadozen cups of coffee and kept at it. Unplugged, replugged, shut down...and now, I'm listening to radio jazz on headphones, and I don't know why because the Activity Monitor still shows the iTunes Helper is not responding(in RED), yet I've got sound again.
I recently got an iPhone 4s, my 1st iPhone, and I guess Helper has something to do with the phone. Some google comments said iTunes Helper could be removed, but do I want to do that? I just checked my wifes' 13" Mac Book Pro and it too has the Helper. I don't know why Helper's not working, or why it wasn't in Start-up, or why it's working now.
I'm pretty much on my own here, and I'd appreciate your advice/ideas. Thanx.