let me guess..
you're working an VIA chipset ?

Try your camera for a change on another chipset (or an usb controller card).

I think having both audio in and video from webcam won't work simultaniously.
For more info about usb devices check out http://www.linux-usb.org/
Maybe you stumble on site dedicated to this camera.
First check out on which chip the camera is based. Maybe you'll find a solution easier then searching on philips.