Index: trunk/psModules/src/imcombine/pmStackReject.c
===================================================================
--- trunk/psModules/src/imcombine/pmStackReject.c	(revision 20826)
+++ trunk/psModules/src/imcombine/pmStackReject.c	(revision 20832)
@@ -258,4 +258,7 @@
     }
 #endif
+
+    // Need to set psImageConvolveMask threading OFF because that would generate threads on top of threads
+    bool oldThreads = psImageConvolveSetThreads(false); // Old value of threading for psImageColvolve
 
     psImage *target = psImageRecycle(convolved, numCols, numRows, PS_TYPE_MASK); // Grown image
@@ -330,4 +333,6 @@
     }
 
+    psImageConvolveSetThreads(oldThreads);
+
 #ifdef TESTING
     {
Index: trunk/psModules/src/imcombine/pmSubtraction.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtraction.c	(revision 20826)
+++ trunk/psModules/src/imcombine/pmSubtraction.c	(revision 20832)
@@ -1238,5 +1238,5 @@
     // and everything is executing psThreadPoolWait, waiting for some other mythical thread to complete the
     // thread's work.
-    psImageConvolveSetThreads(false);
+    bool oldThreads = psImageConvolveSetThreads(false); // Old value of threading for psImageConvolve
 
     if (stride == 0) {
@@ -1333,4 +1333,6 @@
     }
 
+    psImageConvolveSetThreads(oldThreads);
+
     psFree(sys1);
     psFree(sys2);
Index: trunk/psModules/src/imcombine/pmSubtractionMask.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionMask.c	(revision 20826)
+++ trunk/psModules/src/imcombine/pmSubtractionMask.c	(revision 20832)
@@ -137,4 +137,6 @@
     // footprint's distance of those (within 'footprint').
 
+    bool oldThreads = psImageConvolveSetThreads(true); // Old value of threading for psImageConvolve
+
     if (!psImageConvolveMask(mask, mask, PM_SUBTRACTION_MASK_BAD_1,
                              PM_SUBTRACTION_MASK_CONVOLVE_1,
@@ -151,4 +153,6 @@
         return NULL;
     }
+
+    psImageConvolveSetThreads(oldThreads);
 
     return mask;