IIS Stopped Automatically in sharepoint

1. Log on to the server that hosts the service, application pool, or Web site.
2. Click Start, click Administrative Tools, and then click Computer Management.
3. In the navigation pane, expand Services and Applications.

1. Perform one of the following steps based on what element you want to stop or start:
2. For a service, click Services, right-click the service, and then click Stop or Start.

• For an application pool, click Internet Information Services (IIS) Manager, expand the local computer, and double-click Application Pools. Right-click the application pool, and then click Stop or Start.

• For a Web site, click Internet Information Services (IIS) Manager, expand the local computer, and double-click Web Sites or Sites.
• 
  If the server is running Windows Server 2003, right-click the Web site, and then click Stop or Start.
  If the server is running Windows Server 2008, right-click the Web site, point to Manage Web Site, and then click Stop or Start.