While I left Windows XP behind a long time ago as my main operating system, I still run numerous virtual machines running Windows XP in order to test with older versions of Internet Explorer. One problem I've been running into with my VMs is when the Windows Update was running, the CPU would get pegged at 99% – 100% usage, which makes Windows unusable.
I tried a number of things to work around the problem to no avail and finally just decided to shut down Windows Update in order to make the VMs usable. However, that leaves my unable to patch my VMs to make sure they're completely up-to-date.
Today I finally had to update one of my VMs, so I really needed to resolve the problem. After some reading, I found that Microsoft is aware of the problem and that it relates to parsing the update tree to find out which updates are needed. The good news is I found a fix that seems to work for me. The trick is to manually update 2 different Security Updates.
Here's how I finally resolved the problem:
Hope that helps someone!