Windows Updates don't work

If Windows Updates download but fail to install, Microsoft knowledgebase 943144 provides a fix:

http://support.microsoft.com/kb/943144

Cleanest option is to re-register wups2.dll in Windows per KB943144.

To register the Wups2.dll file in Windows, follow these steps: # Stop the Automatic Updates service. To do this, follow these steps: a. Click Start, click Run, type cmd, and then click OK. b. At the command prompt, type the following command, and then press ENTER: net stop wuauserv # Register the Wups2.dll file. To do this, follow these steps: a. At the command prompt, type the following command, and then press ENTER: regsvr32 windir\system32\wups2.dll Note For a computer that is running Windows XP Professional x64 Edition, type the following command, and then press ENTER: regsvr32 windir\syswow64\wups2.dll b. Click OK on each verification message that you receive. # Start the Automatic Updates service. To do this, type the following command at the command prompt, and then press ENTER: net start wuauserv # Exit the command prompt. To do this type exit, and then press ENTER. -—

Per Hubert’s original recommendation, presumably also based on KB943144: —

There is a standalone installer for Windows Update, located for download at

http://download.windowsupdate.com/v7/windowsupdate/redist/standalone/WindowsUpdateAgent30-x86.exe

This is a nice tool if you run into trouble with Windows Update failing.