On March 11, 2008 I had to turn off Windows XP automatic synchronization with an internet time server because the time was wrong on my laptop. I manually set the time and forgot about it. Yesterday I realized that my email message times were off by one hour. I looked at one of my sent emails and it had "Date: Fri, 21 Mar 2008 14:39:48 -0600". I googled and figured out that since I'm in CDT this should be -0500. As a matter of fact emails sent to me from those I work with did in fact have this in the message header: "Fri, 21 Mar 2008 14:34:36 -0500 (CDT)". I couldn't figure out why my machine wasn't updated for the new daylight savings time begin date. I have all the latest Windows XP updates.
I talked to our system admin at OCI and he said I needed to apply this update:928388. I downloaded it, but it said that it was already applied. After digging around some more I found the following "How to configure daylight saving time for Microsoft Windows operating systems". I followed the steps which require you to create and apply a registry file and create and run a vbs script. That fixed the problem.