Help: No audio sometimes to external speakers?

[mac2maverick]

I've had Logitech Z-10 speakers for about 7 months and I'm now having problems. Occasionally lose audio when I open a new app that requires audio. From that point on there is no audio until I restart my computer. If I switch the audio to the internal speakers on my imac it works fine. This only happens once in a while but it's really starting to urk me. I'm wondering if Leopard's upgrade has something to do with it. Anyone have any ideas or had a similar problem?

[mac2maverick]

It might be a problem with a usb hub. Seems to work now that I've by-passed it, although it might just be a coincidence. How do I test a usb hub?

[mac2maverick]

I also had a problem with my Mac Pro not picking up that I had the Logitech Z-10's hooked up to my computer, but after unplugging the speakers and usb connection, waiting 30 seconds and then reconnecting everything, the MP finally recognized them. It seems to be working fine now.