Is your timezone perchance 6 hours offset from GMT? I suspect that if your bios is correct to your timezone, that KDE is attempting to correct to your timezone. Though personally I would not think that is any of KDE's business but should rather set within the rc files. Maybe your system is making the correction twice? I do not know mandrake, but I do know that a kernel option can specify whether time will be stored in GMT or local time, so there could be a mismatch between your kernel setup and what your system is expecting.
Ah, a quick google search proves other people have had similar problems. See for example:
http://archives.mandrakelinux.com/ne...0/msg01064.php
Good luck to you.