Your problem is more fundamental than the unsigned sAPO - for some reason Windows isn't loading your driver at all. From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Ernest_Burghardt@xxxxxxxxxxxx Sent: Tuesday, April 29, 2008 3:13 PM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] installing unsigned APO on SP1 I am attempting to use an unsigned APO onto Vista Ultimate 64-bit w/ SP1... It appears to install correctly and then requests a restart, but if you look closely the Yellow Bang is present in the DeviceManager and it will not load after the restart I view the Driver properties and see your friend and mine, (Code 39) I've set the registry flag HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Audio "DisableProtectedAudioDG"=dword:00000001 and restarted my system, which used to work before... Is there a new workaround to ensure unsigned drivers/APOs will function with Vista x64 SP1? Thanks in advance, Ernie Ernest L. Burghardt Software Engineer Core SW Development Team Logitech Inc. 360-256-3239 (office)