Index: /trunk/src/VBox/Devices/Bus/MsiCommon.cpp
===================================================================
--- /trunk/src/VBox/Devices/Bus/MsiCommon.cpp	(revision 32861)
+++ /trunk/src/VBox/Devices/Bus/MsiCommon.cpp	(revision 32862)
@@ -140,5 +140,5 @@
                     }
 
-                    if (maskUpdated != -1)
+                    if (maskUpdated != -1 && msiIsEnabled(pDev))
                     {
                         for (int iBitNum = 0; i<8; i++)
@@ -199,4 +199,8 @@
     Assert(cVectors > 0);
 
+    if (cVectors != 1)
+        /* We cannot handle multiple vectors yet */
+        return VERR_TOO_MUCH_DATA;
+
     if (cVectors > VBOX_MSI_MAX_ENTRIES)
         return VERR_TOO_MUCH_DATA;