What desktop G4 does he have. I have a MDD and had that same issue, Through various sources I found out that some of the MDD's had bad logic boards installed, which caused this very issue. Under the Apple Care Program, had my logic board replaced and have had no problems seeing either of my external F/W drives. The only problem was that the new logic board over-powered on of my memory slugs which was apparently marginal anyway. It was replaced and have had no problems since. (going on 6 months now) Al