FYI, CiscoWorks on windows somehow "discovers" the system timezone from the name of the timezone settings on the server. If you change the name of the windows timezone (like for Argentina, when applying the "new" summertime patch) then CW looses track and stays in ACT.
If someone knows where the mapping table is, I would be glad to know.
Java maps Windows registry information about timezones to Java timezone names. The file used for the mapping depends on the JVM which is having the problem. The main tzmappings file for the main JVM for LMS is found under NMSROOT\lib\jre\lib\tzmappings. This file should not be edited as its contents are very critical to Java being able to ascertain the correct timezone.