Index: /trunk/src/VBox/Devices/Audio/DevHDA.cpp
===================================================================
--- /trunk/src/VBox/Devices/Audio/DevHDA.cpp	(revision 75316)
+++ /trunk/src/VBox/Devices/Audio/DevHDA.cpp	(revision 75317)
@@ -1400,5 +1400,6 @@
 
                 /* Remove the old stream from the device setup. */
-                hdaR3RemoveStream(pThis, &pStream->State.Cfg);
+                rc2 = hdaR3RemoveStream(pThis, &pStream->State.Cfg);
+                AssertRC(rc2);
 
                 /* Add the stream to the device setup. */
@@ -2909,7 +2910,9 @@
     hdaR3StreamUpdate(pStream, true /* fInTimer */);
 
-    /* Flag indicating whether to kick the timer again for a
-     * new data processing round. */
-    const bool fSinkActive = AudioMixerSinkIsActive(pStream->pMixSink->pMixSink);
+    /* Flag indicating whether to kick the timer again for a new data processing round. */
+    bool fSinkActive = false;
+    if (pStream->pMixSink)
+        fSinkActive = AudioMixerSinkIsActive(pStream->pMixSink->pMixSink);
+
     if (fSinkActive)
     {