One thing to check is whether /etc/localtime is a symbolic link to /usr/share/zoneinfo/Europe/Warsaw or if it is a plain file. It should be a symbolic link, otherwise changes to the timezone data won't take effect.
Another thing to check is whether you have the TZ environment variable set (or set to a value other than Europe/Warsaw) since that could be overriding the system timezone. Other than that, I'm stumped... - todd
