If you can read Spanish, you may like to see Errores 0x80240036 y 0x8024400A u otros problemas con Windows Update en reinstalaciones de Windows XP.
I have seen many questions in forums about a problem on new installations of Windows XP. Some users had issues which led them to reinstall Windows XP. Then, Windows could not search for automatic updates and the Windows Update web site showed an error code like 0x80240036 or 0x8024400A. Update (March 30, 2012): Error code 0x80244019 may also appear.
Note: Windows 2000, which doesn’t receive new updates since July 2010, Windows XP x64 Edition and Windows Server 2003 may also be affected by this problem.
Microsoft had to make changes in its update infrastructure because of the incidents related to the Flame malware. A likely consequence of these changes is that the built-in Windows Update client in Windows XP and the Microsoft servers cannot understand each other anymore. Therefore, the client is not able to upgrade itself to the latest version. The Automatic Updates icon never appears in the notification area and the Windows Update web site shows an error code, even if the Automatic Updates settings are properly configured and enabled.
Note: the proposed solution applies only to the symptoms described in this article. It probably won’t be of much help on other scenarios. If the error codes are different or your computer does not reveal these symptoms, you may look for help at other sources or request assistance on user forums like Microsoft Answers or TechNet Forums.
The solution I have found so far is the following. You should install manually the Windows Update client, version 7.4.7600.226, for 32-bit Windows (x86) or 64-bit Windows (x64). Which version of Windows is running on my computer: 32-bit or 64-bit? This Windows Update client will upgrade itself to the latest version eventually, which is 7.6.7600.256 to date. Microsoft has not made available a standalone installer for this version yet.
Even after installing the client, it may take some time to look for automatic updates. They might appear at least an hour later or Windows may need to be restarted. You can force searching for updates by running wuauclt /detectnow on Start, Run, or in any other way. However, the Windows Update web site should work normally, provided the latest service pack for Windows is installed.