Q: sharepoint 2013 error Page not found 404 i installed new sp 2003 standard trial on w2k8r2sp1 and my domain is on 2003 server with exchange 2003 on seperate system, sp machine is a client of DC, at start up it was working fine, the default page was accessible but when i tried to change authentication method, from NTLM to kerberos now PAGE NOT FOUND error, 
i deleted the default web application and re installed but the error is same , i tried to fix it from IIS but i think i messed up , i can open central admin but default port 80 page is not working . some time i get connection close with full information of iis 7.5 etc. 
i can see only this on page below :::
HTTP/1.1 200 OK
Server: Microsoft-IIS/7.5
Date: Sat, 23 Mar 2013 17:17:57 GMT
Connection: close
i tried it from localhost, system name , ip from the network but no luck . 
any idea ? its my development sp but i am worried if i go for production i might happend again .. 
your help is appreciated :) 
Malik 

A: Reason :
I found that the reason is during the web application creation process IIS is reset and by default. It allows the "Shutdown time limit" which by default is 90 seconds. Sometimes this might not be enough. And hence it forcibly shuts down in 90 seconds.
Resolution Steps (Worked for me): 
Go to application pool of Central Administration.
Right click on it and go to Advanced Settings
In the Process Model section, increase the shutdown time limit to 200 for example.
It is a good idea to restart IIS now.
