请求的表单身份验证失败。原因:提供的票证已过期

我无法使用表单身份验证进行连接,因为我收到以下消息:

Event code: 4005 
Event message: Forms authentication failed for the request. Reason: The ticket supplied has expired. 
Event time: 8/31/2010 3:35:58 PM 
Event time (UTC): 8/31/2010 12:35:58 PM 
Event ID: b566569a3ac244928af9585691f997ef 
Event sequence: 12 
Event occurrence: 1 
Event detail code: 50202 

相关web.config节:

    <machineKey validationKey="DBD8250ABB1B0D07E5F490C0F0D8D7DA783597A0E232177C" decryptionKey="428C3A22DE12A294CAAFBEC7DA6919E80F7D11319D5DB23A" validation="SHA1" />
<authentication mode="Forms">
      <forms loginUrl="/_layouts/customlogin.aspx" path="/" protection="All" timeout="60" slidingExpiration="true" />
    </authentication>

有什么想法吗? 谢谢。