ERROR when add expression to watch

SharpDevelop Version : 4.3.3.9663-463ee024
.NET Version         : 4.0.30319.18408
OS Version           : Microsoft Windows NT 6.1.7601 Service Pack 1
Current culture      : German (Germany) (de-DE)
Running under WOW6432, processor architecture: x86-64
Working Set Memory   : 289524kb
GC Heap Memory       : 88243kb

Unhandled WPF exception
Exception thrown:
System.InvalidOperationException: Der Vorgang ist aufgrund des aktuellen Zustands des Objekts ungültig.
   bei ICSharpCode.TreeView.SharpTreeNodeView.CalculateIndent()
   bei ICSharpCode.TreeView.LinesRenderer.OnRender(DrawingContext dc)
   bei System.Windows.UIElement.Arrange(Rect finalRect)
   bei System.Windows.Controls.Grid.ArrangeOverride(Size arrangeSize)
   bei System.Windows.FrameworkElement.ArrangeCore(Rect finalRect)
   bei System.Windows.UIElement.Arrange(Rect finalRect)
   bei System.Windows.Controls.Control.ArrangeOverride(Size arrangeBounds)
   bei System.Windows.FrameworkElement.ArrangeCore(Rect finalRect)
   bei System.Windows.UIElement.Arrange(Rect finalRect)
   bei MS.Internal.Helper.ArrangeElementWithSingleChild(UIElement element, Size arrangeSize)
   bei System.Windows.Controls.ContentPresenter.ArrangeOverride(Size arrangeSize)
   bei System.Windows.FrameworkElement.ArrangeCore(Rect finalRect)
   bei System.Windows.UIElement.Arrange(Rect finalRect)
   bei System.Windows.Controls.GridViewRowPresenter.ArrangeOverride(Size arrangeSize)
   bei System.Windows.FrameworkElement.ArrangeCore(Rect finalRect)
   bei System.Windows.UIElement.Arrange(Rect finalRect)
   bei System.Windows.Controls.Border.ArrangeOverride(Size finalSize)
   bei System.Windows.FrameworkElement.ArrangeCore(Rect finalRect)
   bei System.Windows.UIElement.Arrange(Rect finalRect)
   bei System.Windows.Controls.Control.ArrangeOverride(Size arrangeBounds)
   bei System.Windows.FrameworkElement.ArrangeCore(Rect finalRect)
   bei System.Windows.UIElement.Arrange(Rect finalRect)
   bei System.Windows.ContextLayoutManager.UpdateLayout()
   bei System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg)
   bei System.Windows.Media.MediaContext.InvokeOnRenderCallback.DoWork()
   bei System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()
   bei System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)
   bei System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)
   bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

---- Recent log messages:
23:28:55.122 [1] DEBUG - Debugger:  - stopped at System.Void ISSqlEdit.MainForm.TreeViewDoubleClick(System.Object sender, System.EventArgs e) because of StepOver from System.Void ISSqlEdit.MainForm.TreeViewDoubleClick(System.Object sender, System.EventArgs e) name="normal"
23:28:55.122 [1] DEBUG - Debugger:  - pausing in user code
23:28:55.125 [1] DEBUG - Debugger: Debugger event: OnPaused()
23:28:55.125 [1] INFO - Jump to current line - start
23:28:55.125 [1] INFO - Open file s:\SharpDevelop\ISSQLEdit\Forms\MainForm.cs
23:28:55.126 [1] INFO - Jump to current line - end (0 ms)
23:28:55.137 [1] INFO - Watch Pad refresh - start
23:28:55.138 [1] INFO - Watch Pad refresh - end (1 ms)
23:28:55.138 [1] INFO - Evaluating: ocmd.CommandText
23:28:55.146 [1] DEBUG - Debugger: Evaluated: ocmd in 3 ms total
23:28:55.149 [1] DEBUG - Debugger: Callback: EvalComplete
23:28:55.151 [1] DEBUG - Debugger: Evaluated: ocmd.CommandText in 7 ms total
23:28:56.453 [1] DEBUG - ActiveContentChanged to ICSharpCode.SharpDevelop.Gui.Pads.WatchPad
23:28:57.748 [1] DEBUG - Activated feature 'Debugger.AddIn.AddWatchCommand', activation=ContextMenu
23:28:59.757 [1] INFO - Watch Pad refresh - start
23:28:59.760 [1] INFO - Watch Pad refresh - end (2 ms)
23:28:59.760 [1] INFO - Evaluating: ocmd.CommandText
23:28:59.761 [1] INFO - Evaluating: found
23:28:59.811 [1] DEBUG - Debugger: Evaluated: ocmd in 35 ms total
23:28:59.816 [1] DEBUG - Debugger: Callback: EvalComplete
23:28:59.830 [1] DEBUG - Debugger: Evaluated: ocmd.CommandText in 54 ms total
23:28:59.838 [1] DEBUG - Debugger: Evaluated: found in 1 ms total
23:29:07.976 [1] DEBUG - Activated feature 'Debugger.AddIn.AddWatchCommand', activation=ContextMenu
23:29:08.998 [1] INFO - Watch Pad refresh - start
23:29:09.053 [1] INFO - Watch Pad refresh - end (55 ms)

---- Post-error application state information:
Installed 3rd party AddIns:
Workbench.ActiveContent: ICSharpCode.SharpDevelop.Gui.Pads.WatchPad
ProjectService.OpenSolution: [Solution: FileName=S:\SharpDevelop\ISSQLEdit\ISSqlEdit.sln, HasProjects=True, ReadOnly=False]
ProjectService.CurrentProject: [CSharpProject: ISSqlEdit]