When you launch IE6 and go to Tools->Windows Update, it asks you if you want "Express" or "Custom" updates, and regardless of what you click, it will then show "Checking for the latest updates for your computer..." with an indeterminate progress bar that just loads forever. I let it sit for five hours, and still nothing. Here are the other things I've tried.
1. Run the Microsoft Fixit tool for Windows Update. This runs and produces interesting output--it says that it "Failed" to address the issue "service registration is missing or corrupt", but if you expand this item to see more details, it says it "succeeded." So I don't know if it failed or succeeded. It also reports "Windows update error 0x80070005".
2. Downloading WindowsUpdateAgent30-x86.exe, as described here, and running it.
3. Confirming my system clock has the correct time.
4. Manually downloading IE 8 (the latest version available for XP) and then trying to run Windows Update again.
5. Attempting to unregister IUCTL.dl as described here. That didn't work for me as there is no IUCTL.dll file at C:\WINNT\System32\IUCTL.dll or C:\WINDOWS\System32\IUCTL.dll.
6. Renamed the Edb.log file, as described here under Advanced manual Methods: Method 1.
7. Turning of Automatic Updates completely, restarting the machine, and then trying to visit the Windows Update page in Internet Explorer again. This was in case there was a conflict between manually visiting the Windows Update site, and an automatic download/installation of a Windows Update.
8. Manually downloading the "network installation package" of XP SP3 and reinstalling SP3. Installation completed without error, but no change in behavior.
If the issue is still not fixed, it can be a very critical problem with your computer affecting your personal data and the Windows Operating System. You will have to chat with our Experts or you can check with your local technician to get the problems fixed with very high priority.