Here is Solution..
private void dgrid_MouseClick(object sender, MouseEventArgs e)
{
dgrid.ContextMenuStrip = null;
}
private void dgrid_CellMouseUp(object sender, DataGridViewCellMouseEventArgs e)
{
dgrid.ContextMenuStrip = null;
}
private void dgrid_CellMouseDown(object sender, DataGridViewCellMouseEventArgs e)
{
if (e.RowIndex >= 0)
{
dgrid.ContextMenuStrip = contextMenuStrip2;
}
}