WCF服务在IIS 6中仅在最初几分钟内工作

我开发了一个WCF服务和silverlight客户端，当我在安装了iis 5.1的windows xp中托管该服务时，它完全按照预期工作

当我在windows server 2003 R2中托管iis 6时，它会在最初几分钟（大约20分钟）内工作，然后停止工作

当我访问服务时，我得到了HTTP 500

我使用的设置是

检查匿名访问和集成身份验证

我的服务配置如下

<system.serviceModel>
<behaviors>
  <serviceBehaviors>
    <behavior name="">
      <serviceMetadata httpGetEnabled="false"/>
      <serviceDebug includeExceptionDetailInFaults="false"/>
    </behavior>
  </serviceBehaviors>
</behaviors>
<bindings>
  <customBinding>
    <binding name="SilverlightApplication1.Web.GetData.customBinding0">
      <binaryMessageEncoding/>
      <httpTransport/>
    </binding>
  </customBinding>
</bindings>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true"/>
<services>
  <service name="SilverlightApplication1.Web.GetData">
    <endpoint address="" binding="customBinding" bindingConfiguration="SilverlightApplication1.Web.GetData.customBinding0" contract="SilverlightApplication1.Web.GetData"/>
    <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
  </service>
</services>

我的silverlight客户端配置是

<client>
        <endpoint address="http://----/InternalBorrow/GetData.svc"
            binding="customBinding" bindingConfiguration="CustomBinding_GetData"
            contract="ServiceReference1.GetData" name="CustomBinding_GetData" />
    </client>

有人能帮我解决问题吗