I finally got the code onto my Dell box and installed the serial card so I could get a kernel stack of the crash I was seeing when stopping audio capture on the Pinnacle 880e. It turns up other people were reporting the same issue on the HVR-900.
Per Robert's suggestion (and after seeing the stack dump), I replaced the usb_unlink_urb() call with a call to usb_kill_urb(), and like magic the crash went away (the isoc_irq apparently wasn't being canceled). Sent email to Mauro and Douglas, and if they agree I'll push a patch.
Now that the audio doesn't crash my system, I can finally get back to getting the audio working for the Pinnacle 880e.
