Have you ever rendered and Excel, Word, or PDF document with ASP.NET and disabled the button when the user clicked "Export To Excel" so that they would only click it once? Then only to find out the the button is still disabled after Response.End() and you cannot enable it again?
protected void Page_Load(object sender, EventArgs e)
+ BtnPrint.ClientID + ".disabled=true;"
+ Page.ClientScript.GetPostBackEventReference(BtnPrint, null));
//Renable the button after 10 seconds
string Script = @"";
Script = Script.Replace("$BTNAME", BtnPrint.ClientID);
Page.ClientScript.RegisterStartupScript(GetType(), "script", Script);