var xPos = 300;
var yPos = 200; 
var step = 1;
var delay = 30; 
var height = 0;
var Hoffset = 0;
var Woffset = 0;
var yon = 0;
var xon = 0;
var pause = true;
var interval;

document.write('<DIV id=img1 style="Z-INDEX: 100; LEFT: 1px; WIDTH: 174px; POSITION: absolute; TOP: 1px; HEIGHT: 100px; visibility:visible; border:1px solid #ccc"><iframe  style="position:absolute;z-index:-1;width:174px;height:100px;top:0;left:0;scrolling:no;" frameborder="0" src="about:blank"></iframe><a href="http://b847112.xici.net" target="_blank"><img src="images/bbs.jpg" alt="ad"></a></DIV>');

img1.style.top = yPos;
function changePos(){
	width = document.body.clientWidth;
	height = document.body.clientHeight;
	Hoffset = img1.offsetHeight;
	Woffset = img1.offsetWidth;
	img1.style.left = xPos + document.body.scrollLeft;
	img1.style.top = yPos + document.body.scrollTop;
	if (yon) 
	{yPos = yPos + step;}
	else 
	{yPos = yPos - step;}
	if (yPos < 0) 
	{yon = 1;yPos = 0;}
	if (yPos >= (height - Hoffset)) 
	{yon = 0;yPos = (height - Hoffset);}
	if (xon) 
	{xPos = xPos + step;}
	else 
	{xPos = xPos - step;}
	if (xPos < 0) 
	{xon = 1;xPos = 0;}
	if (xPos >= (width - Woffset)) 
	{xon = 0;xPos = (width - Woffset);   }
}
function start() {
	img1.visibility = "visible";
	interval = setInterval('changePos()', delay);
}
function pause_resume() 
{
	if(pause) {
		clearInterval(interval);
		pause = false;}
	else {
		interval = setInterval('changePos()',delay);
		pause = true; 
	}
}
start();