Time Zone Editor is a small program by Microsoft that can be
used to create and edit time zone entries in Date/Time settings.
It is because in some Windows 95/98/NT/2000 versions Time Zone
records are incomplete or incorrect, especially Daylight Savings start and end
times (DST). As a result, ATC may show a wrong time for such timezones, and
in the case if your current timezone information is incorrect, the times in
all other time zones will be misleading.
You may download Microsoft Time Zone Editor
here (23 Kb).
In short, just select the desired time zone from list, press
Edit button, and set appropriate values for Daylight Saving Time start and end.
To find more, see editor’s Help.