I have an AVStream audio capture filter mini driver for a USB audio device. The descriptors for this filter expose two pins (one bridge and one actual audio pin), and the topology connects these two pins via one internal filter node (ADC type). Under Win7 this filter appears to run fine. If I launch a DAW (I am currently testing with Reaper), under preferences if I select WDM Kernel Streaming as the audio system my driver appears. If I select my device and instance and arm a track I can capture a valid audio wave form. I have a 440 hz tone feeding the device and the waveform present appears to be a valid sine wave. If I install this same driver under XP sp3 and launch Reaper I again see that the device is enumerating under WDM Kernel Streaming system. If I select the device and try to record, the cursor just seems to sit at time "0". Under the debugger I see the capture pin get instanced and the system changes the state of the pin from KSSTATE_STOP to KSSTATE_ACQUIRE, but it goes no further. I've verified that the state change to acquire returns success so I'm a bit baffled as to what is wrong. If I run GraphEdit and instance the capture filter, I can smart render the pin (it connects up to default DS renderer) and run the graph and actually hear the tone from my generator. I'm at a loss to explain what it is that the XP audio system doesn't like about the filter. Neither the filter, nor the pin are exposing an automation table. I'm just letting the AVStream framework handle any properties. I don't see the system querying for any audio specific properties (latency, position) which would lead me to believe that maybe I need to include one or more. Anyone have any insights into what could possibly prevent graph from transitioning all the way to KSSTATE_RUN, or some way to possibly debug why? mike