Microsoft ASP.NET offers two options for out-of-proc Session state. One of these options is the ASP.NET Session State Service (Aspnet_state.exe). Like any Windows Service, this service can be configured by using the Windows 
Services window (Services.msc). In the 
Services window, you can configure the 
Startup Type for each service. The 
Startup Type determines the execution of the service when the computer has been restarted. The 
Startup Type has the following valid options:
After you install any ASP.NET hotfix, the 
Startup Type will be set to 
Manual. Therefore, if the 
Startup Type was set to 
Automatic before we install the hotfix, we would expect the ASP.NET State Service  to start automatically after a restart occurs. However, that behavior would not occur because the 
Startup Type is set to 
Manual. If you want the ASP.NET State Service to start automatically, change the 
Startup Type to 
Automatic after you install  any ASP.NET hotfix.