Make sure that when a subdevice is instantiated, you create the wave and topology ports/miniports, register the physical connection, THEN register the wave subdevice and finally the topology subdevice. Likewise when removing a subdevice, unregister the topology subdevice first, then the wave subdevice, the physical connection and finally release the ports. Apparently if it's not done in that order, a race condition can occur which does what you're describing. Jeff ----- Original Message ----- From: StarXing@xxxxxxxxxxxxxx To: wdmaudiodev@xxxxxxxxxxxxx Sent: Friday, June 05, 2009 12:49 PM Subject: [wdmaudiodev] Problems about dynamic audio subdevice on Vista Hello everyone, I am develping an audio driver which implement dynamic audio subdevice on windows vista. The audio subdevice can be instantiated/uninstantiated on behalf of user's request through device IO control. After instantiating the audio subdevice, the user would like to locate thate audio endpoints through MMDevice API and render through that device. In most cases these are running without trouble except two strange issues. 1) Can't locate the audio subdevice through MMDevice API although we can see it in system audio control panel 2) Can't see the audio subdevice in system audio control panel In case 2, the audio subdevice will appear in system audio control panel if we restart the "Windows Audio Endpoint Builder" services. Any pointers on these 2 issues are greatly appreciated. Thanks and regards, HW