Silverlight Virtualization Recycling Errors

Question

I have the following XAML for Silverlight 3:

<ItemsControl MaxHeight="400"
              VirtualizingStackPanel.VirtualizationMode="Recycling" >
   <ItemsControl.Template>
      <ScrollViewer>
         <ItemsPresenter />
      </ScrollViwer>
   </ItemsControl.Template>
   <ItemsControl.ItemsPanel>
      <ItemsPanelTemplate>
         <VirtualizingStackPanel/>
      </ItemsPanelTemplate>
   </ItemsControl.ItemsPanel>
   <ItemsControl.ItemTemplate>
      <DataTemplate>
         <!-- All my item stuff -->
      </DataTemplate>
   </ItemsControl.ItemTemplate>
 </ItemsControl>

But I find I get a bunch of the following errors whenever I scroll:

System.Windows.Data Error: BindingExpression path error: 
    'ItemDescription' property not found on 'MyObject' 'MyObject' (HashCode=4187856).
    BindingExpression: Path='ItemDescription' DataItem='MyObject' (HashCode=4187856); 
    target element is 'System.Windows.Controls.TextBlock' (Name=''); 
    target property is 'Text' (type 'System.String')..

This goes away if I turn off Recycling. Anyone got a clue how to prevent this?