Important Updates that are currently downloaded but that have not yet been installed must be downloaded again from the Windows Update Web site or from the Microsoft Update Web site.
Windows Vista and Windows Server 2008
Click Start Collapse this imageExpand this image, type notepad in the Start Search box, and then press ENTER.
Copy and then paste the following commands into the new Notepad document:
net stop wuauserv

cd %systemroot%\SoftwareDistribution

ren Download Download.old

net start wuauserv
On the File menu, click Save As.
In the Save in box, click Desktop.
In the Save as type box, click All Files.
In the File name box, type Rename.bat.
Click Save.
On the File menu, click Exit to exit Notepad.
On your desktop, right-click Rename.bat, and then click Run as Administrator.

Collapse this imageExpand this imageIf you are prompted for an administrator password or for confirmation, type the password, or click Continue.
Try to install the update by using the Windows Update Web site or the Microsoft Update Web site.
If the update is installed successfully, delete the Rename.bat file that you saved in steps 1 through 7.
Windows 2000, Windows XP, and Windows Server 2003
Click Start, click Run, type notepad in the Open box, and then click OK.
Copy and then paste the following commands into the new Notepad document:
net stop wuauserv

cd %systemroot%\SoftwareDistribution

ren Download Download.old

net start wuauserv
On the File menu, click Save As.
In the Save in box, click Desktop.
In the Save as type box, click All Files.
In the File name box, type Rename.bat.
Click Save.
On the File menu, click Exit to exit Notepad.
On your desktop, double-click Rename.bat.
Try to install the update by using the Windows Update Web site or the Microsoft Update Web site.
If the update is installed successfully, delete the Rename.bat file that you saved in steps 1 through 7.
Notes
If the problem is not resolved, go to method 2.
If the problem is resolved and if you can successfully download and install updates, you can safely delete the Download.old folder to recover disk space.
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Method 2: Download and install the update manually
Determine the Microsoft Knowledge Base article number of the failed update. To do this, do one of the following:
View the error code message.
View the update history on the Windows Update Web site or on the Microsoft Update Web site. To do this, follow these steps:
Visit the following Microsoft Update Web site:
http://update.microsoft.com (http://update.microsoft.com)
Under Options, click Review your update history.
In the Update column, determine the Microsoft Knowledge Base article number of the failed update.
Visit the following Windows Download Web site:
http://www.microsoft.com/windows/downloads/default.aspx (http://www.microsoft.com/windows/downloads/default.aspx)
In the Search box on the Downloads Web page, type the article number that you located in step 1, and then click Go.

Note If the article number that is listed for the update is KB123456, type 123456 in the Search box on the Downloads Web page, and then click Go.
Browse through the list of returned content, and locate the Knowledge Base article that has a link to the download.

Note You may be prompted to validate Windows. If you are prompted, follow the instructions to validate Windows, and then continue to download the update.
Click Download, and then click Save when you are prompted to save the download. Save the download to your desktop.
After the download has finished, click Open to install the update.
Note The installation of the update may fail if the update is incorrect for your version of Windows.