Index: /branches/eraser6/pluginsRewrite/Eraser.Manager/Task.cs
===================================================================
--- /branches/eraser6/pluginsRewrite/Eraser.Manager/Task.cs	(revision 2490)
+++ /branches/eraser6/pluginsRewrite/Eraser.Manager/Task.cs	(revision 2491)
@@ -99,7 +99,8 @@
 			{
 				if (value == null)
-					throw new ArgumentNullException();
+					throw new ArgumentNullException("Task.Executor cannot be null");
 				if (executor != null)
-					throw new InvalidOperationException();
+					throw new InvalidOperationException("A task can only belong to one " +
+						"executor at any one time");
 
 				executor = value;