Index: /trunk/src/VBox/Additions/WINNT/Installer/VBoxGuestAdditions.nsi
===================================================================
--- /trunk/src/VBox/Additions/WINNT/Installer/VBoxGuestAdditions.nsi	(revision 37814)
+++ /trunk/src/VBox/Additions/WINNT/Installer/VBoxGuestAdditions.nsi	(revision 37815)
@@ -804,9 +804,9 @@
   !insertmacro InstallLib DLL NOTSHARED REBOOT_NOTPROTECTED "$%PATH_OUT%\bin\additions\d3d9.dll" "$g_strSystemDir\dllcache\d3d9.dll" "$TEMP"
 
-  ; Save original DLLs ...
+  ; Save original DLLs (only if msd3d*.dll does not exist) ...
   SetOutPath $g_strSystemDir
   IfFileExists "$g_strSystemDir\msd3d8.dll" +1
     CopyFiles /SILENT "$g_strSystemDir\d3d8.dll" "$g_strSystemDir\msd3d8.dll"
-  IfFileExists "$g_strSystemDir\msd3d8.dll" +1
+  IfFileExists "$g_strSystemDir\msd3d9.dll" +1
     CopyFiles /SILENT "$g_strSystemDir\d3d9.dll" "$g_strSystemDir\msd3d9.dll"
 
@@ -857,5 +857,5 @@
     !insertmacro InstallLib DLL NOTSHARED REBOOT_NOTPROTECTED "$%VBOX_PATH_ADDITIONS_WIN_X86%\d3d9.dll" "$SYSDIR\dllcache\d3d9.dll" "$TEMP"
 
-    ; Save original DLLs ...
+    ; Save original DLLs (only if msd3d*.dll does not exist) ...
     SetOutPath $SYSDIR
     IfFileExists "$SYSDIR\dllcache\msd3d8.dll" +1
Index: /trunk/src/VBox/Additions/WINNT/Installer/VBoxGuestAdditionsW2KXP.nsh
===================================================================
--- /trunk/src/VBox/Additions/WINNT/Installer/VBoxGuestAdditionsW2KXP.nsh	(revision 37814)
+++ /trunk/src/VBox/Additions/WINNT/Installer/VBoxGuestAdditionsW2KXP.nsh	(revision 37815)
@@ -595,5 +595,5 @@
     Delete /REBOOTOK "$g_strSystemDir\dllcache\d3d8.dll"
     Rename /REBOOTOK "$g_strSystemDir\dllcache\msd3d8.dll" "$g_strSystemDir\dllcache\d3d8.dll"
-  IfFileExists g_strSystemDir\dllcache\msd3d9.dll" 0 +2
+  IfFileExists "$g_strSystemDir\dllcache\msd3d9.dll" 0 +2
     Delete /REBOOTOK "$g_strSystemDir\dllcache\d3d9.dll"
     Rename /REBOOTOK "$g_strSystemDir\dllcache\msd3d9.dll" "$g_strSystemDir\dllcache\d3d9.dll"