Index: trunk/ppStack/src/ppStackLoop.c
===================================================================
--- trunk/ppStack/src/ppStackLoop.c	(revision 23367)
+++ trunk/ppStack/src/ppStackLoop.c	(revision 23576)
@@ -59,4 +59,13 @@
     if (!stack) {
         psError(PS_ERR_IO, false, "Unable to initialise stack threads.");
+        psFree(options);
+        return false;
+    }
+    psFree(options->cells); options->cells = NULL;
+
+    // Prepare for combination
+    if (!ppStackCombinePrepare(stack, options, config)) {
+        psError(PS_ERR_UNKNOWN, false, "Unable to prepare for combination.");
+        psFree(stack);
         psFree(options);
         return false;