Index: /trunk/src/VBox/HostDrivers/Support/win/SUPDrv-win.cpp
===================================================================
--- /trunk/src/VBox/HostDrivers/Support/win/SUPDrv-win.cpp	(revision 51954)
+++ /trunk/src/VBox/HostDrivers/Support/win/SUPDrv-win.cpp	(revision 51955)
@@ -3582,5 +3582,6 @@
         /* XP & W2K3 doesn't have this function exported, so we've cooked up a
            few alternative in the assembly helper file that uses the code in
-           ZwQueryVolumeInformationFile with a different eax value. */
+           ZwReadFile with a different eax value.  We figure the syscall number
+           by inspecting ZwQueryVolumeInformationFile as it's the next number. */
 # ifdef RT_ARCH_X86
         uint8_t const *pbCode = (uint8_t const *)(uintptr_t)ZwQueryVolumeInformationFile;
Index: /trunk/src/VBox/HostDrivers/Support/win/SUPDrvA-win.asm
===================================================================
--- /trunk/src/VBox/HostDrivers/Support/win/SUPDrvA-win.asm	(revision 51954)
+++ /trunk/src/VBox/HostDrivers/Support/win/SUPDrvA-win.asm	(revision 51955)
@@ -51,7 +51,7 @@
 ;
 ; Faking up ZwQueryVirtualMemory on XP and W2K3 where it's not exported.
-; Using ZwQueryVolumeInformationFile as a helper.
+; Using ZwReadFile as a helper as it has the name number of parameters.
 ;
-extern  IMPNAME(ZwQueryVolumeInformationFile@20)
+extern  IMPNAME(ZwReadFile@24)
 
 BEGINPROC supdrvNtQueryVirtualMemory_Xxx
@@ -79,5 +79,5 @@
 
 supdrvNtQueryVirtualMemory_Jump:
-        mov     edx, IMP2(ZwQueryVolumeInformationFile@20)
+        mov     edx, IMP2(ZwReadFile@24)
         lea     edx, [edx + 5]
         jmp     edx