Index: /trunk/src/VBox/Additions/WINNT/Installer/VBoxDrvInst.cpp
===================================================================
--- /trunk/src/VBox/Additions/WINNT/Installer/VBoxDrvInst.cpp	(revision 46708)
+++ /trunk/src/VBox/Additions/WINNT/Installer/VBoxDrvInst.cpp	(revision 46709)
@@ -138,9 +138,14 @@
  * @param   pszName             The DLL name.
  */
-static HMODULE loadSystemDll(const char *pszName)
+static HMODULE loadInstalledDll(const char *pszName)
 {
     char   szPath[MAX_PATH];
-    UINT   cchPath = GetSystemDirectoryA(szPath, sizeof(szPath));
-    size_t cbName  = strlen(pszName) + 1;
+    UINT   cchPath = GetModuleFileNameA(NULL, szPath, sizeof(szPath));
+    if (cchPath && cchPath <= sizeof(szPath))
+    {
+        char *pszSlashFile = strrchr(szPath, '\\');
+        if (pszSlashFile)
+            cchPath = pszSlashFile - szPath;
+    }
     if (cchPath + 1 + cbName > sizeof(szPath))
         return NULL;
@@ -164,5 +169,5 @@
 {
     HRESULT hr = S_OK;
-    HMODULE hDIFxAPI = loadSystemDll("DIFxAPI.dll");
+    HMODULE hDIFxAPI = loadInstalledDll("DIFxAPI.dll");
     if (NULL == hDIFxAPI)
     {