Disable LinkButton in ASP.NET

.aspx code

<asp:ImageButton ID="mngBtnExcel" runat="server" Enabled="false" ImageUrl="~/Images/Recepients_32x32.gif" onclick="mngBtnExcel_Click1"/>

In the above code even though i have set Enabled="false" i was experiencing a post back when click on the image button with the IE browser. I added the below code in the page load event which solved my issue.

.cs code

mngBtnExcel.Enabled = false;
mngBtnExcel.OnClientClick = "return false;";