4. Type
net stop wuauserv
5. Press <Enter>. Automatic updates service is now disabled.
6. Type
regsvr32 %windir%\system32\wups2.dll and press <Enter>.
If you are using Windows XP Professional x64 edition, type
regsvr32 %windir%\system64\wups2.dll and press <Enter>
7. You will receive verification messages. Click Ok.
8. Now, enable automatic updates services. To do so, type:
net start wuauserv
9. Type Exit and press <Enter>. You should now return to the normal Windows mode.
After performing the above steps, download and install Windows update agent. To do so, visit Microsoft website and download install Windows update agent.
For more information, visit the following links:
http://support.microsoft.com/ph/6527#tab0
http://support.microsoft.com/kb/906602
You should now be able to install windows updates without any problem.