SD Error When Closed!

SharpDevelop Version : 5.1.0.5134-RC-d5052dc5
.NET Version         : 4.5.50938
OS Version           : Microsoft Windows NT 6.1.7601 Service Pack 1
Current culture      : Chinese (Simplified, PRC) (zh-CN)
Running under WOW6432, processor architecture: x86-64
Working Set Memory   : 115832kb
GC Heap Memory       : 21777kb

Unhandled exception terminated the workbench
Exception thrown:
System.NullReferenceException: Object reference not set to an instance of an object.
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.WriteConfig(XmlDocument doc)
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.SaveSideBarViewConfig()
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.<Initialize>b__5_0(Object , EventArgs )
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at ICSharpCode.SharpDevelop.Gui.WorkbenchSingleton.OnWorkbenchUnloaded()
   at ICSharpCode.SharpDevelop.Sda.CallHelper.RunWorkbenchInternal(Object settings)

---- Recent log messages:
09:09:22.709 [1] DEBUG - NavigationService
    ActiveViewContent: Program.cs
              Subview: ${res:FormsDesigner.DesignTabPages.SourceTabPage}
09:09:22.709 [1] DEBUG - ActiveViewContentChanged to [AvalonEditViewContent D:\2.R18\1.Ins IOxel\C# InsCtr\Program.cs]
09:09:22.795 [1] DEBUG - Update Foldings
09:09:23.143 [8] DEBUG - Resolved (Line 1, Col 1) to
09:09:23.503 [1] DEBUG - Resolved (Line 16, Col 41) to
09:09:29.874 [5] DEBUG - Resolved (Line 22, Col 28) to
09:09:58.424 [1] DEBUG - Resolved (Line 32, Col 6) to
09:09:58.437 [8] DEBUG - Resolved (Line 32, Col 6) to
09:09:59.235 [5] DEBUG - Resolved (Line 312, Col 13) to
09:09:59.646 [1] DEBUG - Service startup: ICSharpCode.SharpDevelop.Templates.ITemplateService
09:10:33.450 [1] DEBUG - Service startup: ICSharpCode.SharpDevelop.Workbench.IShutdownService
09:10:33.474 [1] DEBUG - Saving memento of '[AvalonEditViewContent D:\2.R18\1.Ins IOxel\C# InsCtr\Program.cs]' to key '1e13ec5:D:\2.R18\1.INS IOXEL\C# INSCTR\PROGRAM.CS'
09:10:33.502 [1] DEBUG - ActiveViewContentChanged to
09:10:33.502 [1] DEBUG - ActiveContentChanged to
09:10:33.502 [1] DEBUG - OpenedFileClosed: D:\2.R18\1.Ins IOxel\C# InsCtr\Program.cs
09:10:33.517 [1] INFO - CurrentProject changed to null
09:10:33.584 [11] DEBUG - Serializing 6 files to C:\Users\zhangxu1\AppData\Local\Temp\SharpDevelop5.1\InsCtr.8bcb05e8.prj
09:10:33.585 [1] INFO - Saving layout file: C:\Users\zhangxu1\AppData\Roaming\ICSharpCode\SharpDevelop5\layouts\Default.xml
09:10:33.592 [1] INFO - Saving layout file: C:\Users\zhangxu1\AppData\Roaming\ICSharpCode\SharpDevelop5\layouts\Default.xml
09:10:33.613 [1] DEBUG - ActiveWorkbenchWindowChanged to
09:10:33.613 [1] DEBUG - CompilerMessageView: Combined 2 appends.
09:10:33.632 [1] INFO - Unloading services...
09:10:33.632 [1] WARN - Exception during unloading
--> Exception:
System.NullReferenceException: Object reference not set to an instance of an object.
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.WriteConfig(XmlDocument doc)
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.SaveSideBarViewConfig()
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.<Initialize>b__5_0(Object , EventArgs )
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at ICSharpCode.SharpDevelop.Gui.WorkbenchSingleton.OnWorkbenchUnloaded()
   at ICSharpCode.SharpDevelop.Sda.CallHelper.RunWorkbenchInternal(Object settings)
09:10:33.634 [1] INFO - Finished running workbench.
09:10:33.634 [1] FATAL - System.NullReferenceException: Object reference not set to an instance of an object.
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.WriteConfig(XmlDocument doc)
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.SaveSideBarViewConfig()
   at ICSharpCode.SharpDevelop.Gui.TextEditorSideBar.<Initialize>b__5_0(Object , EventArgs )
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at ICSharpCode.SharpDevelop.Gui.WorkbenchSingleton.OnWorkbenchUnloaded()
   at ICSharpCode.SharpDevelop.Sda.CallHelper.RunWorkbenchInternal(Object settings)

---- Post-error application state information:
Installed 3rd party AddIns:
ProjectService.CurrentSolution: <null>
ProjectService.CurrentProject: <null>
Workbench.ActiveContent: <null>