> In VS.2005 Using VB.NET on a windows XP (sp2) fully patched.
>
> I have a project that has a Microsoft DataGridView on it.
> Occasionally, when I click on a column header, I get:
>
> ArgumentExceptionIsUnHandled
> At least one object must implement IComparable
>
> this problem is Intermittent, it doesn't happen all the time,
> but happens about once in every five clicks of the column header.
>
> I am at a total loss as to what this could be.
>
> Thanks in Advance,
>
> Laurence
>
> Here is the detail:
>
> System.ArgumentException was unhandled
>   Message="At least one object must implement IComparable."
>   Source="mscorlib"
>   StackTrace:
>        at System.Collections.Comparer.Compare(Object a, Object b)
>        at
> System.Windows.Forms.DataGridViewRowCollection.RowComparer.CompareObjects(Object
> value1, Object value2, Int32 rowIndex1, Int32 rowIndex2)
>        at
> System.Windows.Forms.DataGridViewRowCollection.RowArrayList.CustomQuickSort(Int32
> left, Int32 right)
>        at System.Windows.Forms.DataGridViewRowCollection.Sort(IComparer
> customComparer, Boolean ascending)
>        at System.Windows.Forms.DataGridView.SortInternal(IComparer
> comparer, DataGridViewColumn dataGridViewColumn, ListSortDirection
> direction)
>        at System.Windows.Forms.DataGridView.Sort(DataGridViewColumn
> dataGridViewColumn, ListSortDirection direction)
>        at
> System.Windows.Forms.DataGridView.OnColumnHeaderMouseClick(DataGridViewCellMouseEventArgs
> e)
>        at System.Windows.Forms.DataGridView.OnMouseClick(MouseEventArgs e)
>        at System.Windows.Forms.Control.WmMouseUp(Message& m,
> MouseButtons button, Int32 clicks)
>        at System.Windows.Forms.Control.WndProc(Message& m)
>        at System.Windows.Forms.DataGridView.WndProc(Message& m)
>        at
> System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
>        at
> System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
>        at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr
> hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
>        at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&
> msg)
>        at
> System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32
> dwComponentID, Int32 reason, Int32 pvLoopData)
>        at
> System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32
> reason, ApplicationContext context)
>        at
> System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32
> reason, ApplicationContext context)
>        at System.Windows.Forms.Application.Run(Form mainForm)
>        at MiscellaneousProjects.frmSearch.Main() in
> C:\vbdev\MiscellaneousProjects\Client
> Application\MiscellaneousProjects\MiscellaneousProjects\frmSearch.vb:line 3
>        at System.AppDomain.nExecuteAssembly(Assembly assembly, String[]
> args)
>        at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence
> assemblySecurity, String[] args)
>        at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
>        at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
>        at System.Threading.ExecutionContext.Run(ExecutionContext
> executionContext, ContextCallback callback, Object state)
>        at System.Threading.ThreadHelper.ThreadStart()
>