The first burner -- the older of the two -- is completely nonresponsive. The light is constantly flickering even though there's no disc inside; and it won't open when I push the button or try to open it from Windows. I've removed and reinstalled it without any change.
The second burner opens but only reads and writes CD's, not DVD's. If I insert a DVD (blank or burned), it does not recognize the format.
I'd be happy to provide additional information if you need more specifics.