From Klaus' wiki
In order to have the correct date and time shown you may need to change the timezone information.
Follow these steps as root user:
- Locate your local timezone in /usr/share/zoneinfo/Europe/, e.g. Copenhagen for Denmark
- Change the file /etc/timezone to contain only one single line: Europe/Copenhagen if Denmark is your local timezone otherwise fit to your needs
- Copy the file /usr/share/zoneinfo/Europe/Copenhagen to /etc/localtime - still if you're in Denmark
- Reboot and check that the time information is correct - CEST for Central European Summer Time or, in wintertime, CET Central European Time.