[VB.NET]我设置了关机,但怎样才能取消关机啊!!!

<script type="text/javascript"><!--
google_ad_client = "pub-8333940862668978";
/* 728x90, 创建于 08-11-30 */
google_ad_slot = "4485230109";
google_ad_width = 728;
google_ad_height = 90;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>

我设置了关机,但怎样才能取消关机啊!!!
我设置了关机,但怎样才能取消关机啊??????
__________________________________________________________________________
我是用VB.NET设置了定时关机了,,但是我想取消另设置一个,
怎样才能取消上次的关机呢?????
__________________________________________________________________________
怎麼設定的就怎麼取消....
__________________________________________________________________________
如: Shell( shutdown.exe /s /f /t 30 )
30秒之后就会关机了!!!
还有没有办法挽救啊!!!!
__________________________________________________________________________
shutdown -a
__________________________________________________________________________
楼上正解
__________________________________________________________________________