Opening & closing Form multiple time give error

In my application I am opening & closing form multiple time. This form contains picture Box & Image list. While reopening Form i am getting error

An unexpected error has occurred in .exe file

After clicking details it gives

Exception error in System.Windows.Forms.Imagelist.setImageSize()

While closing form using cancel button on form I had written code.

private void btnCancel_click(Object Sender, Eventargs e)
   if(pictureBox1.Image != null)
       pictureBox1.Image = null;
    this.Dialogresult = DialogResult.Cancel();

Dear @Madhav
I’m afraid I’m not a UI expert.

As a general debug recommendation, I suggest you create a new minimal project which contains only a simple form and does nothing but opening and closing this form.
This makes it much easier to track down the source of the problem. For example I’m not sure whether you should call pictureBox1.Image.Dispose(), or whether this is automatically done when the form closes.

Regards, Andy