Last click Event get Fired on browser back Click and click another button

protected void RadGrid1_SelectedIndexChanged(object sender, EventArgs e)
{




foreach (GridDataItem dataItem in RadGrid1.Items)
{
// MsgBox("FDDFD")
if (dataItem.Selected)
{
// use the column UniqueName (categorydescription ) to access the cell and get its Text
MyGlobalClass.comcode = dataItem["column9"].Text;
MyGlobalClass.ItemName = dataItem["column1"].Text;
// MyGlobalClass.Tqty = dataItem("column5").Text;

Response.Redirect("SectorN.aspx");

// Page.ClientScript.RegisterStartupScript(Me.[GetType](), "OpenWindow", "window.open('SectorN.aspx','_newtab');", True)
// Response.Write("window.open('Drill.aspx','_blank')")

// Page.ClientScript.RegisterStartupScript(Page.[GetType](), "open_window", String.Format("void(window.open('{0}', 'child_window'));", "SectorN.aspx"), True)



}
}



}
// when i fire fllowing even but fire above event (after browser back )


protected void RadButton1_Click(object sender, EventArgs e)
{
//ScriptManager.RegisterStartupScript(this, GetType(),
// "ServerControlScript", "jydrfyjfyj", true);

//ClientScript.RegisterStartupScript(this.GetType(), "JSScript", "dyjdfyjdfy");

Response.Redirect("Drill.aspx");
//this.RadComboBox4.SelectedIndex = -1;
// RadComboBox4.Text = "Select Sector";
// load();

}

i have main page-M then i click grid row and redirect to page-A.. after that i click the back button on browser then i will go to page-M. Now i click button1(Redirect to other page), BUT it will fire last row click evet and go to page-A...????