Index: /trunk/src/VBox/Devices/Storage/DrvSCSI.cpp
===================================================================
--- /trunk/src/VBox/Devices/Storage/DrvSCSI.cpp	(revision 64656)
+++ /trunk/src/VBox/Devices/Storage/DrvSCSI.cpp	(revision 64657)
@@ -788,8 +788,8 @@
     PDRVSCSIREQ pReq = (PDRVSCSIREQ)hIoReq;
 
-    if (pReq->cbXfer <= pReq->cbBuf)
+    if (pReq->cbXfer && pReq->cbXfer <= pReq->cbBuf)
         *pcbResidual = pReq->cbBuf - pReq->cbXfer;
     else
-        *pcbResidual = 0; /* Overflow/Underrun error. */
+        *pcbResidual = 0; /* Overflow/Underrun error or no data transfers. */
     return VINF_SUCCESS;
 }