Index: trunk/psModules/src/imcombine/pmSubtractionMatch.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 23944)
+++ trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 23989)
@@ -830,12 +830,14 @@
     psFree(mask);
 
+    // XXX raise an error here or not?
+    if (isnan(stats->robustMedian)) {
+        psFree(stats);
+        return PM_SUBTRACTION_MODE_ERR;
+    }
+
     psLogMsg("psModules.imcombine", PS_LOG_INFO, "Median width ratio: %lf", stats->robustMedian);
     pmSubtractionMode mode = (stats->robustMedian <= 1.0 ? PM_SUBTRACTION_MODE_1 : PM_SUBTRACTION_MODE_2);
     psFree(stats);
 
-    // XXX EAM : I think Paul left some test code in here.  I've commented these lines out
-    // return PM_SUBTRACTION_MODE_2;
-    // exit(1);
-
     return mode;
 }