Ventrilo, Logitech Premium USB Headset 350 and System Preferences

Hi all,
I have some troubles using ventrilo on my G5 (same problems also on a new iMac).

Ventrilo is working, I'm using it with World of Warcraft, and using it with a Logitech Premium USB Headset 350 (but the problem happen also with Logitech 250).

After some times I'm using Ventrilo, this is very random, people in Ventrilo stop hearing me. I noted that opening the System Preferences, checking the Sound panel, the Logitech is selected as sound in, but the visual signal on the panel is blank (if I speak on the microphone no signal is visualized).

What I need to do is to disconnect the Logitech from the USB and reconnect it. I need also to exit from Ventrilo and relaunch it.

Then all is working good again, naturally till this happen again (may be 5 minutes after as 30 minutes).

I've also tried to remove Ventrilo and its preferences and reinstalling it. This assuming that the cause of all this is Ventrilo and not MacOSX. But this happen also on a new iMac...

Thanks for any help!