不住变动的图片

<script> 
var widths=310; 
var heights=310; 
var counts=6; 
img1=new Image ();img1.src='image/bg.jpg'; 
img2=new Image ();img2.src='image/bg1.jpg'; 
img3=new Image ();img3.src='image/bg2.jpg'; 
img4=new Image ();img4.src='image/dh_bg.jpg'; 
img5=new Image ();img5.src='image/xxyBg.jpg'; 
img6=new Image ();img6.src='image/logo.jpg'; 

var nn=1; 
var key=0; 
function change_img() 
{if(key==0){key=1;} 
else if(document.all) 
{document.getElementById("pic").filters[0].Apply();document.getElementById("pic").filters[0].Play(duration=2);} 
eval('document.getElementById("pic").src=img'+nn+'.src'); 
for (var i=1;i<=counts;i++){document.getElementById("xxjdjj"+i).className='axx';} 
document.getElementById("xxjdjj"+nn).className='bxx'; 
nn++;if(nn>counts){nn=1;} 
tt=setTimeout('change_img()',4000);} 
function changeimg(n){nn=n;window.clearInterval(tt);change_img();} 
document.write('<style>'); 
document.write('.axx{padding:1px 7px;border-left:#cccccc 1px solid;}'); 
document.write('a.axx:link,a.axx:visited{text-decoration:none;color:#fff;line-height:12px;font:9px sans-serif;background-color:#666;}'); 
document.write('a.axx:active,a.axx:hover{text-decoration:none;color:#fff;line-height:12px;font:9px sans-serif;background-color:#999;}'); 
document.write('.bxx{padding:1px 7px;border-left:#cccccc 1px solid;}'); 
document.write('a.bxx:link,a.bxx:visited{text-decoration:none;color:#fff;line-height:12px;font:9px sans-serif;background-color:#D34600;}'); 
document.write('a.bxx:active,a.bxx:hover{text-decoration:none;color:#fff;line-height:12px;font:9px sans-serif;background-color:#D34600;}'); 
document.write('</style>'); 
document.write('<div style="width:'+widths+'px;height:'+heights+'px;overflow:hidden;text-overflow:clip;">'); 
document.write('<div><img id="pic" style="border:0px;filter:progid:dximagetransform.microsoft.wipe(gradientsize=1.0,wipestyle=4, motion=forward)" width='+widths+' height='+heights+' /></div>'); 
document.write('<div style="filter:alpha(style=1,opacity=10,finishOpacity=80);background: #888888;width:100%-2px;text-align:right;top:-12px;position:relative;margin:1px;height:12px;padding:0px;margin:0px;border:0px;">'); 
for(var i=1;i<counts+1;i++){document.write('<a href="javascript:changeimg('+i+');" id="xxjdjj'+i+'" class="axx" target="_self">'+i+'</a>');} 
document.write('</div></div>'); 
change_img(); 
</script>