When the subject installation fails, the Windows Update.log file contains error 0x80070643.

To fix this problem, use the following procedure, exiting when the problem is resolved:

01. Use Windows Explorer to navigate to %SystemRoot%\System32\CatRoot2.

02. Right-click the Edb.log file and Rename as Edb.old.

03. Try to use Windows Update to install Windows XP updates.

04. Use Windows Explorer to navigate to %SystemRoot%\System32.

05. Right-click CatRoot2 and Rename it as CatRoot2Old.

06. Try to use Windows Update to install Windows XP updates.

07. Open a CMD.EXE window and enter the following commands, pressing Enter after each one. Press OK to the succeeded message:

regsvr32 licdll.dll
regsvr32 regwizc.dll

08. Try to use Windows Update to install Windows XP updates.

09. If the Microsoft Root Authority or NO LIABILITY ACCEPTED, (c)97 VeriSign, Inc. certificates under Trusted Root Certification Authorities has been removed:

  • On another computer that has the certificate, use Internet Explorer to open Tools / Internet Options / Content tab / Certificates.
  • Select the Trusted Root Certification Authorities tab.
  • Select Microsoft Root Authority and press Export. Create the .CER file on a floppy or a share.
  • On the 'broken' computer, use Internet Explorer to open Tools / Internet Options / Content tab / Certificates.
  • Select the Trusted Root Certification Authorities tab.
  • Press Import.
  • Press Next.
  • Browse to the file you exported and press Open.
  • Press Next.
  • Select Automatically select the certificate store based on the type of certificate.
  • Press Next and Finish.
10. Try to use Windows Update to install Windows XP updates.

11. Open a CMD.EXE window.

12. Type attrib -r -s -h C:\WUTEMP\*.* and press Enter. (WUTEMP may be on a different drive letter.)

13. Type del /q C:\WUTEMP\*.* and press Enter.

14. Try to use Windows Update to install Windows XP updates.

15. If you still cannot install updates, disable any software firewall and anti-virus and stop any 3rd party software that is currently running.