Hello Ken, > I don't have the code in front of me at the moment but I'll take a > closer look tomorrow at the portcls and WDK sample code Could you please take a look to a portcls code that implements stream state transitions? Testing my driver under Vista RTM, I noticed that sometimes a rendering IMiniportWavePciStream object is released (a destructor is called) when the stream is in KSSTATE_PAUSE. It happens only if I open an endpoint properties, select "Advanced" tab and click "Test" button, not every time but very often, and never happens on common audio processing, when DirectSound/MME are used. I already wrote about this: //www.freelists.org/archives/wdmaudiodev/01-2007/msg00112.html Regards, Eugene ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/