Index: /trunk/src/VBox/Devices/Graphics/DevVGA_VBVA.cpp
===================================================================
--- /trunk/src/VBox/Devices/Graphics/DevVGA_VBVA.cpp	(revision 71655)
+++ /trunk/src/VBox/Devices/Graphics/DevVGA_VBVA.cpp	(revision 71656)
@@ -2147,4 +2147,6 @@
     else if (idxQuery == VBOX_VBVA_CONF32_MAX_RECORD_SIZE)
         uValue = VBVA_MAX_RECORD_SIZE;
+    else if (idxQuery == UINT32_MAX)
+        uValue = UINT32_MAX; /* Older GA uses this for sanity checking. See testQueryConf in HGSMIBase.cpp on branches. */
     else
         ASSERT_GUEST_MSG_FAILED_RETURN(("Invalid index %#x\n", idxQuery), VERR_INVALID_PARAMETER);