Noise when using Canopus ADVC110

[peterm]

My ADVC110 works very well with Vidi - I really like to hear the audio
(in sync!) while recording. iMovie take note!

However, after a while, background noise gets louder and louder. It
seems to get worse it I have other firewire devices plugged in (disk
and iSight). I am running OSX 10.5.6 on a PowerMac G5.

Anyone else experience this? Can it be related to un-used audio
channels (there was a post along those lines somewhere else).

Switching off the ADVC110 then on again, makes the problem go away.
For a while. Perhaps 15-30 minutes. So I am not sure if I should be
looking for a hardware or software problem.

While the loud noise is present, I can quit vidi and re-start it -
noise is still there.

But if I quit vidi and immediately record using iMovie the noise it
not present. So this hints at something that vidi is doing.

Any suggestions?
-PeterM