diff --git a/src/UndoHistory.py b/src/UndoHistory.py
index f14a6600c..278aca582 100644
--- a/src/UndoHistory.py
+++ b/src/UndoHistory.py
@@ -133,14 +133,16 @@ class UndoHistory(ManagedWindow.ManagedWindow):
 
     def _paint_rows(self,start,end,selected=False):
         if selected:
-            (fg,bg) = get_colors(self.tree,gtk.STATE_SELECTED)
+            (fg, bg) = get_colors(self.tree,gtk.STATE_SELECTED)
         else:
             fg = bg = None
-
         for idx in range(start,end+1):
-            the_iter = self.model.get_iter( (idx,) )
-            self.model.set(the_iter,2,fg)
-            self.model.set(the_iter,3,bg)
+            try:
+                the_iter = self.model.get_iter( (idx,) )
+                self.model.set(the_iter, 2, fg)
+                self.model.set(the_iter, 3, bg)
+            except ValueError:
+                pass
             
     def _response(self, obj,response_id):
         if response_id == gtk.RESPONSE_CLOSE:
@@ -182,7 +184,7 @@ class UndoHistory(ManagedWindow.ManagedWindow):
 
     def clear(self):
         self.undodb.clear()
-        self.undodb.abort_possible = False
+        self.db.abort_possible = False
         self.update()
         if self.db.undo_callback:
             self.db.undo_callback(None)
diff --git a/src/gen/db/txn.py b/src/gen/db/txn.py
index 3ec6f2a58..dc3929b85 100644
--- a/src/gen/db/txn.py
+++ b/src/gen/db/txn.py
@@ -169,6 +169,8 @@ class DbTxn(defaultdict):
         While the list is an arbitrary index of integers, it can be used
         to indicate record numbers for a database.
         """
+        if self.first is None or self.last is None:
+            return []
         if not reverse:
             return xrange(self.first, self.last+1)
         else: