这是我们花一段时间才能找到这个问题的答案，因为我被告知，我是比较它的另一个IIS7服务器，以同样的方式已经设置，由同一个人。

It's taken us a while to find the answer to this as I had been informed that another IIS7 server I was comparing it to had been setup in the same way, by the same person.

原来使用的Plesk这是收到此错误的网站已经设置了服务器，而其他服务器一直没。

It turns out the server with the websites which were receiving this error had been setup using Plesk, whereas the other server had not been.

这似乎Plesk设置的空闲超时时间为5分钟的应用程序池，这是什么导致这个错误。

It seems Plesk sets the Idle-Timeout to 5 minutes on the application pools, which is what was causing this error.

要改变这一做到以下几点：

To change this do the following:

1. 开启IIS


2. 单击应用程序池节点


3. 找到您的Web应用程序的应用程序池


4. 右键单击并选择Advanace设置


5. 设置空闲超时（分钟）属性设置为0或增加至30多分钟