Index: /trunk/src/VBox/Devices/VMMDev/VMMDev.cpp
===================================================================
--- /trunk/src/VBox/Devices/VMMDev/VMMDev.cpp	(revision 43319)
+++ /trunk/src/VBox/Devices/VMMDev/VMMDev.cpp	(revision 43320)
@@ -536,4 +536,7 @@
         pThis->pDrv->pfnUpdateGuestInfo2(pThis->pDrv, uFullVersion, pszName, pInfo2->additionsRevision, pInfo2->additionsFeatures);
 
+    /* Clear our IRQ in case it was high for whatever reason. */
+    PDMDevHlpPCISetIrqNoWait (pThis->pDevIns, 0, 0);
+
     return VINF_SUCCESS;
 }
@@ -923,5 +926,9 @@
 
             if (pThis->fu32AdditionsOk)
+            {
                 pRequestHeader->rc = VINF_SUCCESS;
+                /* Clear our IRQ in case it was high for whatever reason. */
+                PDMDevHlpPCISetIrqNoWait (pThis->pDevIns, 0, 0);
+            }
             else
                 pRequestHeader->rc = VERR_VERSION_MISMATCH;