how to disable header click in windows forms

Hi HK33,

Although your question is quite "BAD" I try to start the guessing to work out what may be your problem. You are expecting someone to "work/think" for you, but you don't bother to formulate your question with a little effort - see OriginalGriffs comment. But with this "behaviour" you are not alone on this forum - I just can't get "used" to it...

That said, let's try to find your Problem:

I assume (those things you didn't think someone should know in order to help you):
* You use a System.Windows.Forms.DataGridView
* You are using the CellClick Event of your System.Windows.Forms.DataGridView
* Your exception happens when you try to get a cell with the indices you got from the EventArgs inside a CellClick handler (method)

So the trick could be just to add some logic to your handler.

private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{
    // No row was clicked (e.g. Header)
    if (e.RowIndex < 0)
    {

    }
    // No column was clicked (e.g. RowHeader)
    else if (e.ColumnIndex < 0)
    {

    }
    // valid cell
    else
    {
    }
}

If this does not solve your problem try to improve your question and show the problematic/relevant code.

Kind regards

Johannes