LXDE - Lightweight X Desktop Environment

There is a mistake I see every time when I'm turning off my laptop... After
choosing "exit" from Openbox menu or "logout" option from lxpanel menu,
nice window appears on my screen. In both cases size and overall look of
such window are bit different, but buttons and text are exactly the same.
Somewhere above all buttons (turn off, logout, hibernate, suspend, etc.)
there is huge text, something like "do you want to log out LXDE Session?".
In Polish it should be called "Wylogować sesję LXDE?", instead of that
first word is "Wologować". It's nothing critical, but it's still annoying.
I was trying to fix it on my own, but translation files
(/usr/share/locale/pl/) are not simple text files...