Update check stops Windows XP
Users and administrators are reporting in forums that some PCs are becoming overloaded when users search for the latest Microsoft updates. On affected computers 100% of CPU capacity is utilised by the svchost process, thereby freezing the Windows desktop. The problem occurs with both the automatic and manual updates on the Microsoft update website.
Microsoft has provided a patch to fix the problem in the Microsoft Installer (MSI), which can be downloaded under the Knowledge Base number KB927891. However, as Microsoft's WSUS development team explain in their blog, the patch is only effective if users also install Version 3.0 of the Windows Update Agent (WUA). Microsoft plans to distribute this new version of the agent in the next few days via the automatic update system. The MSI patch should find its way onto all Windows PCs via this route in early June.
If the problem persists despite installing the update, the following workaround may help: stop the "Automatic Update" and "Background Intelligent Transfer Service" system services, then delete the complete C:\Windows\SoftwareDistribution folder which contains downloaded update packages and status information. After restarting both services, Windows will rebuild the contents of the folder.