Index: lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/service/ForumService.java
===================================================================
diff -u -rb036e6dd6d2afe9c0e0b9143c9be3af1d53a1e0e -r099202c58808065e706b1bd6c1a849b0d0399032
--- lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/service/ForumService.java	(.../ForumService.java)	(revision b036e6dd6d2afe9c0e0b9143c9be3af1d53a1e0e)
+++ lams_tool_forum/src/java/org/lamsfoundation/lams/tool/forum/service/ForumService.java	(.../ForumService.java)	(revision 099202c58808065e706b1bd6c1a849b0d0399032)
@@ -842,7 +842,18 @@
 	}
 
 	Forum toContent = Forum.newInstance(fromContent, toContentId);
-
+	
+	// remove session Messages from topics
+	for (ForumCondition condition : toContent.getConditions()) {
+	    Iterator<Message> conditionMessageIter = condition.getTopics().iterator();
+	    while (conditionMessageIter.hasNext()) {
+		Message conditionMessage = conditionMessageIter.next();
+		if (conditionMessage.getToolSession() != null) {
+		    conditionMessageIter.remove();
+		}
+	    }
+	}
+	
 	// save topics in this forum, only save the author created topic!!! and reset its reply number to zero.
 	Set topics = toContent.getMessages();
 	if (topics != null) {