Index: src/java/org/quartz/impl/StdSchedulerFactory.java
===================================================================
--- src/java/org/quartz/impl/StdSchedulerFactory.java	(revision 656)
+++ src/java/org/quartz/impl/StdSchedulerFactory.java	(working copy)
@@ -1106,7 +1106,9 @@
 
         JobRunShellFactory jrsf = null; // Create correct run-shell factory...
 
-        UserTransactionHelper.setUserTxLocation(userTXLocation);
+        if (userTXLocation != null) {
+            UserTransactionHelper.setUserTxLocation(userTXLocation);
+        }
 
         if (wrapJobInTx) {
             jrsf = new JTAJobRunShellFactory();