Index: Common/vtkLine.cxx
===================================================================
RCS file: /cvsroot/VTK/VTK/Common/vtkLine.cxx,v
retrieving revision 1.84
diff -u -r1.84 vtkLine.cxx
--- a/Common/vtkLine.cxx	2 May 2004 04:33:58 -0000	1.84
+++ b/Common/vtkLine.cxx	29 Jun 2004 01:07:06 -0000
@@ -273,6 +273,10 @@
   //
   num = p21[0]*(x[0]-p1[0]) + p21[1]*(x[1]-p1[1]) + p21[2]*(x[2]-p1[2]);
   denom = vtkMath::Dot(p21,p21);
+  if (denom == 0.0)
+    {
+    return -1.0;
+    }
 
   // trying to avoid an expensive fabs
   tolerance = VTK_TOL*num;