If you receive Windows Update error 8024402C while checking for updates, you might need to do one of the following:
This error might be caused by a program running on your computer that is preventing Windows Update Services (SVCHOST) from accessing the Internet. Programs that might do this include firewalls, anti-spyware software, web accelerators, Internet security or antivirus programs. and proxy servers. If you have any of these programs running, you might need to turn them off while downloading and installing updates. Microsoft recommends you turn them back on after updating your computer. For more information, see Windows Update error 80072efd.
If the computer is connected to a network at work, contact a network administrator. You probably receive updates using Windows Server Update Services (WSUS), a service that enables network administrators to deploy and manage updates for all computers on a network. For more information about WSUS, go to the Windows Server Update Services (WSUS) website.
If your computer is usually connected to a network at work (for example, if you use a mobile PC but you are currently using it at home or at another location), you probably receive updates using WSUS and can not receive updates by connecting directly to the Internet or to another network, such as a home network. To solve the problem, connect to the network at work and try checking for updates again, or contact a network administrator. To see if your computer's updates are being managed by a WSUS server, do the following:
Open Windows Update by clicking the Start button , clicking All Programs, and then clicking Windows Update.
If your computer is managed by WSUS, you will see You receive updates: Managed by your system administrator near the bottom of the page.
If your computer is being managed by WSUS, you can connect to the WSUS server either at your work, or through a virtual private network (VPN). If this doesn't work, you can try connecting directly to the Microsoft Updates website by doing the following:
Open Windows Update by clicking the Start button , clicking All Programs, and then clicking Windows Update.
Click Check online for updates from Microsoft Update Service.
If the computer is connected directly to the Internet or to a home network (and never connected to a network at work), you might need to set Internet Explorer to automatically detect local area network (LAN) settings so Windows Update can go online to obtain updates. To do this, follow these steps:
Open Internet Explorer by clicking the Start button , and then clicking Internet Explorer.
Click the Tools button, click Internet Options, click the Connections tab, and then click LAN settings.
Under Automatic configuration, select the Automatically detect settings check box, and then click OK.
If the problem persists after you have explored the options above, see this Knowledge Base article on the Microsoft Help and Support website or go to the Windows Update Support Center website to request support by e‑mail.
Help and Support search term: WindowsUpdate_8024402C
http://windows.microsoft.com/en-US/windows-vista/Windows-Update-error-8024402C