Open IIS on Windows 7 for website publishing.
However, after OPENING IIS, The default website cannot be opened, showing The Service Unavailable HTTP Error 503. The Service is Unavailable.

Open IIS and discover that the application pool has stopped. After startup, browse again, or not, the application pool will always stop itself.
 
When you open the Windows log, you can see the error message
Windows cannot find the local configuration file and is using a temporary configuration file to let you log in. Changes made to this configuration file are lost when you log out.

Baidu of, combine the plan that netizen provides next, change the setting of program pool.
IIS- Application pool – Advanced Settings – Process Model – identity. Change the built-in account to NetworkService


Ok, done.
Launch the application pool, browse the web page, and successfully see the IIS default page.

 
Used to apache, Nginx, now to toss iis really tired, always inexplicable problems. Ah…
Server system: Window Server 2008 R2
Here is my problem:
HTTP Error 503. The service is unavailable.”
Later found that the application pool opened, inexplicably stopped!!
Solutions:
Select the application pool used – & GT; Advanced Settings, find the “Identity” property in the “Process Model” bar, click the pop-up window, select “NetworkService” in the “Built-in Accounts”, ok, restart the application pool, restart the website.
Reference: http://blog.csdn.net/vivian8725118/article/details/18661683