DirectX problem?

Everytime I try to run the AirFoil speakers on VISTA, it says this in the error log:

--------------------------------------------
Crash occured in AirfoilSpeakers at 9/26/2009 4:32:06 PM: Microsoft.DirectX.DirectSound.AccessDeniedException
------------- exception level 0 -------------
Message:
Error in the application.
Source
Microsoft.DirectX.DirectSound
Stack Trace:
at Microsoft.DirectX.DirectSound.Buffer.Play(Int32 priority, BufferPlayFlags flags)
at RogueAmoeba.AirfoilSpeakers.Modal.LocalAudioPlayer.AudioRunThread()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
Target Site:
Void Play(Int32, Microsoft.DirectX.DirectSound.BufferPlayFlags)
----end exception----
-------- end dump --------

What should I do?????

Thanks.