If you have original Windows and it is daily updating your windows but it fails in installing the windows update or you are manually downloading the updates by few things you can install your files. First download the windows Installer 3.1 and restart your system if the system still fails in installing the updates the second method try to stop the Windows update service from your startup menu and typing msconfig in your RUN command you have to search for windows services and remove the tick mark from the windows update or else type as services.msc in the RUN command and click ok and right click on the windows update and choose it as stop.

And open the My computer or the Windows Explorer and confirm that all the hidden files & folders are being shown and search for WINDOWS\SoftwareDistribution\Download and delete all the files within this folder and after that search for

WINDOWS\SoftwareDistribution\EventCache and delete all the files. And again start the Windows Update services and even confirm that its properties are being set as automatic and download the latest version of the Windows Update Agent and save it on your desktop. Shutdown all your programs or any other web browser and double click on the downloaded windows update agent and run the application.
If you get any error that your update agent is already being installed then click on the Start button on the taskbar and select the RUN command from the start menu and click on the browse button where your windows update agent was being installed and select it as on the desktop and click on the open button and again click on the windows update agent.exe file and click after the last quotation mark in the line and enter /wuforce so it will display as C:\Documents and Settings\username\Desktop\WindowsUpdateAgent30-x86.exe" /wuforce and click ok to install the Windows update.

Download the file kb927891 update to your desktop and shutdown all your programs and run the downloaded file which is saved on your desktop.