the way you are using clearInterval is not correct.
its should be something like this:

var t;
//to start
t=setTimeout("someFunction()",1000);
//to stop
clearTimeout(t);

i guess this would help you:
http://punbb.informer.com/forums/topic/17351/how-to-add-a-font-file-to-my-website/

hi
dont use innerHTML property with text box. its property of tag element like div.
use
document.getElementById('txtSMS').value="hiiiii";

or see an example;

<%@ Page Language="C#"...