Stream Buffer Engine in a service

I am trying to write a service which use the Stream Buffer Engine to do background recording. A GUI can connect and disconnect from the service to view the stream at anytime. I have the recording "service" working in a non-service executable, but when it runs as an service, the StreamBufferSource filter in the GUI gets the error that another process has the file opened. Using ProcMon I can see that it is one of the backing files that it is choking on. In my tests currently, the service and GUI are running under my accou开发者_如何学编程nt. I am calling IStreamBufferConfigure3::SetNamespace(NULL) in both the service and the client.

Any thoughts?