when we drag and drop appointments frequently then this exception occurs. How to handle it. Sometimes during the working an exception occurs in week view, when we drag some appointment or just click on appointmetn object. Stack trace is given below. " at Infragistics.Win.UltraWinSchedule.ScheduleDrawUtility.SetDayHeaderAppearancePropertyDefaultValuesOffice2007(Outlook2007ColorScheme colorScheme, Boolean isToday, Boolean isHotTracking, AppearanceData& defaultAppData)\r\n at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingle.ResolveDayHeaderAppearance(DateTime date, AppearanceData& appData, AppearancePropFlags& requestedProps, Owner owner, Boolean isHotTracking)\r\n at Infragistics.Win.UltraWinSchedule.MonthViewSingle.DayNumberUIElement.InitAppearance(AppearanceData& appearance, AppearancePropFlags& requestedProps)\r\n at Infragistics.Win.UltraWinSchedule.MonthViewSingle.DayNumberUIElement.AddChildUIElements(UIElementsCollection oldElements)\r\n at Infragistics.Win.UltraWinSchedule.MonthViewSingle.DayNumberUIElement.PositionChildElements()\r\n at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)\r\n at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)\r\n at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)\r\n at Infragistics.Win.UIElement.VerifyChildElements(Boolean recursive)\r\n at Infragistics.Win.UIElement.VerifyChildElements()\r\n at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingle.OnSelectedActivitiesChanged(SelectedActivitiesCollectionBase selectedActivities)\r\n at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingleBase.OnCalendarInfoChanged(CalendarInfoChangedEventArgs args)\r\n at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingle.OnCalendarInfoChanged(CalendarInfoChangedEventArgs args)\r\n at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingleBase.OnCalendarInfoChanged(Object sender, CalendarInfoChangedEventArgs args)\r\n at Infragistics.Win.UltraWinSchedule.CalendarInfoChangedEventHandler.Invoke(Object sender, CalendarInfoChangedEventArgs e)\r\n at Infragistics.Win.UltraWinSchedule.UltraCalendarInfo.OnCalendarInfoChanged(CalendarInfoChangedEventArgs e)\r\n at Infragistics.Win.UltraWinSchedule.UltraCalendarInfo.FireCalendarInfoChangedEventHelper(PropChangeInfo propChangeInfo, PropertyIds propId)\r\n at Infragistics.Win.UltraWinSchedule.UltraCalendarInfo.OnSubObjectPropChanged(PropChangeInfo propChangeInfo)\r\n at Infragistics.Shared.SubObjectBase.NotifyPropChange(PropChangeInfo trigger)\r\n at Infragistics.Shared.SubObjectBase.NotifyPropChange(Enum propId)\r\n at Infragistics.Win.UltraWinSchedule.SelectedActivitiesCollectionBase.ContentsChangedHelper(ContentsChangeType contentsChangeType, SubObjectBase[ activities, Boolean clearExisting)\r\n at Infragistics.Win.UltraWinSchedule.SelectedActivitiesCollectionBase.AddHelper(SubObjectBase[ activities, Boolean clearExisting)\r\n at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingleBase.Infragistics.Win.ISelectionManager.SelectItem(ISelectableItem item, Boolean clearExistingSelection)\r\n at Infragistics.Win.SelectionStrategyExtended.OnMouseDown(ISelectableItem item, MouseMessageInfo& msginfo, Boolean forceDrag)\r\n at Infragistics.Win.SelectionStrategyExtendedAutoDrag.OnMouseDown(ISelectableItem item, MouseMessageInfo& msginfo)\r\n at Infragistics.Win.SelectionStrategyExtended.OnMouseMessage(ISelectableItem item, MouseMessageInfo& msginfo)\r\n at Infragistics.Win.ControlUIElementBase.ProcessMouseDownHelper(Object sender, MouseEventArgs e)\r\n at Infragistics.Win.ControlUIElementBase.ProcessMouseDown(Object sender, MouseEventArgs e)\r\n at Infragistics.Win.Utilities.ProcessEvent(Control control, ProcessEvent eventToProcess, EventArgs e)\r\n at Infragistics.Win.UltraControlBase.OnMouseDown(MouseEventArgs e)\r\n at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingleBase.OnMouseDown(MouseEventArgs e)\r\n at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)\r\n at System.Windows.Forms.Control.WndProc(Message& m)\r\n at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)\r\n at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)\r\n at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)\r\n at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)\r\n at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)\r\n at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)\r\n at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)\r\n at System.Windows.Forms.Application.Run()\r\n at Coronado.Framework.PFM.Program.Main() in C:\\Coronado Versions\\BetaRelease1700\\desktop\\Framework\\PFM\\Program.cs:line 79\r\n at System.AppDomain.nExecuteAssembly(Assembly assembly, String[ args)\r\n at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[ args)\r\n at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()\r\n at System.Threading.ThreadHelper.ThreadStart_Context(Object state)\r\n at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)\r\n at System.Threading.ThreadHelper.ThreadStart()" DeclaringType: {Name = "ScheduleDrawUtility" FullName = "Infragistics.Win.UltraWinSchedule.ScheduleDrawUtility"} How to handle this exception. Kindly help.