I have patched but an appointment in my calendar shows the wrong time. Why?

Q: I patched my Windows XP SP2 PC.  I have Exchange 2003 SP2 on my network.  I did not patch Exchange, or Outlook.  I have a recurring appointment set up.  I checked the time of the appointment for the date of March 14, and it shows up fine (correct time).
A: Delete the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{Random GUID of the program that relates to the V1 of the tool}