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scrollbar problem.. Messages   Related Types This message was discovered on microsoft.public.dotnet.framework.windowsforms. Responses highlighted in red are from those people who are likely to be able to contribute good, authoratitive information to this discussion. They include Microsoft employees, MVP's and others who IMHO contribute well to these kinds of discussions. Post a new message to this list... Paul Lo Dear all, I'm writting a .net winForm application with C#, but I'm getting the following exception when the user scrolls a scrollbar. The strange thing is that the exception happens only some of the time, and seems pretty random. However, once an exception occurs with a scrollbar and when I choose 'continue', that particular scrollbar will raise the exception everytime I click on it from that point on. Anyone encounter the same problem before? Any solution to this problem? At the very least I wanna know how I could catch that exception.. Thanks~! Paul ************** Exception Text ************** System.NullReferenceException: Object reference not set to an instance of an object. at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ContainerControl.WndProc(Message& m) at System.Windows.Forms.UserControl.WndProc(Message& m) at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) Reply to this message...        mavisahdas (VIP) Hi paul, Before answering this question... i want to know the following things So you have a scroll bar control in ur application was is a scroll bar attached to some other control. Have u handled any event i mean do u have any Scroll event attached to that scroll bar. This null reference exception will occur only when the object is not initialised or only when it is dereferenced. So, there are cases where the objects get disposed... if you have any code written in the scroll event, pls send me that code also. Answer these question this will help me solving this problem.. you can reach me at Click here to reveal e-mail address, Click here to reveal e-mail address. With regards, Sadha Sivam S, Microsoft Community Star, KMG Info Tech. Vist http://www.dotnetspider.com for more dot net updates "Paul Lo" wrote: [Original message clipped] Reply to this message...        Paul Lo Hi Sadha, Thanks for your reply. Actually I have both types of scrollbar that you mentioned. I have a scrollbar control that is attached to a customer control that I made. And Yes, I have the scroll event attached to this scrollbar control. Besides, I am also using MDI, the mdi child got a scrollbar when it is displayed inside the mdi parent form. Both of these scrollbars got the same problem, occasionally. That really made me frustrated. If there is some object that I forgot to initialize or dereferenced, guess the error should happen every time, but it's not the case. It seems strange to me that such exception is generated from System.Windows.Forms.UnsafeNativeMethods.CallWindowProc, and in fact everything in the call stack are internal method calls within the framework. Hope the above could give you some clue to my problem.. Paul "mavisahdas" <Click here to reveal e-mail address> wrote in message news:Click here to reveal e-mail address... [Original message clipped] Reply to this message...        Mavisahdas hi paul, Can u pls send the code of ur scroll event... With regards, Sadha Sivam S, Microsoft Community Star, KMG Info Tech, Bangalore, Mobile: 9880397583 Reply to this message...        Charles Collins I have an application that is throwing the same error, but only when run through terminal server. We have yet to see it in any other instance and it is totally random and sporadic. A solution to this issue would be greatly welcomed here too. Charles "Paul Lo" <Click here to reveal e-mail address> wrote in message news:exja%Click here to reveal e-mail address... [Original message clipped] Reply to this message...     System.IntPtr System.NullReferenceException System.Windows.Forms.ContainerControl System.Windows.Forms.Control System.Windows.Forms.NativeWindow System.Windows.Forms.ScrollableControl System.Windows.Forms.UserControl Ad MBR BootFX Best-of-breed application framework for .NET projects, developed by Matthew Baxter-Reynolds and MBR IT

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