Index: vtkOpenGLExtensionManager.cxx
===================================================================
RCS file: /cvsroot/VTK/VTK/Rendering/vtkOpenGLExtensionManager.cxx,v
retrieving revision 1.33
diff -u -r1.33 vtkOpenGLExtensionManager.cxx
--- vtkOpenGLExtensionManager.cxx	25 Nov 2008 13:02:21 -0000	1.33
+++ vtkOpenGLExtensionManager.cxx	17 Feb 2009 22:42:47 -0000
@@ -481,8 +481,11 @@
 
   const char *version =
     reinterpret_cast<const char *>(glGetString(GL_VERSION));
-  int driverMajor, driverMinor;
-  sscanf(version, "%d.%d", &driverMajor, &driverMinor);
+  int driverMajor = 0, driverMinor = 0;
+  if (version)
+    {
+	sscanf(version, "%d.%d", &driverMajor, &driverMinor);
+    }
 
   version_extensions = vtkgl::GLVersionExtensionsString();
   endpos = 0;