Brian,

I don't think that this issue is related to a particular device. I'm having the same problem with my driver. See the post "Inquiry Re: SetupDiEnumDeviceInterfaces prerequisits" two threads below this one.

I modified the Toaster class installer to make my own class. It seems like everything works except for SetupDiEnumDeviceInterfaces from a user application. Unfortunately, I need this function to get a device path for CreateFile.

I don't see my interface GUID in the registry. If you install the Toaster example, you will see the interface GUID in the registry. I don't yet know if this is related.

It looks like I can hard-code a device name in IoCreateDevice, but this is supposed to be the wrong way to do it.