Why Does Audio Suddenly Drop Out?

Question

OK, geniuses: Running an Ensemble with 7.2.1 on a G5 Dual 2GHZ, 10.4.7. Without warning, I hear a crack and the audio dissappears. iTunes, Logic, almost any (see below) audio, until I restart the G5. Then everything is hunky-dory until the next time. This happens every fifteen minutes or so. ALTERNATIVELY, instead of a complete drop out of audio, I get an unbelievable level of distortion, liike blown output transistors.
Clues: -Apogee has generously replaced what they thought was a bad unit - new unit makes no difference!
-Presence of additional Firewire drives, control surfaces, etc. makes no difference.
-Ensemble WILL continue to pass live audio, ie. an open mic, just not anything from Logic or iTuens of the Audio/MIDI SetUp config noise.
-Latency has no effect. I've changed it from 128 to 1024.
-I AM using the brand new driver for Ensemble, and using all their particulars for starting up Ensemble prior to the G5, etc.
Ideas?
Power Mac G5 Dual 2 Ghz   Mac OS X (10.4.7)  

Answer 1

Yeah, that's what I originally though when I acquired the Ensemble and used the driver then available. Since then there have been several updates, all incresing stability, and particularly valuable is the latest, which makes it possible for me to solve the problem by restarting the Ensemble, rather than having to reboot the G5.
Also, it wouldn't explain why everything works OK on the MacBook Pro, would it?
Significantly, about half the time, instead of dropping all the way out, the audio just becomes hugely distorted.
Ideas?