Polish translation file disables sidebar content

Hi Tim,
I’ve got a strange problem with Polish translation files. Files downloaded directly from www.remarpro.com.
So, problem is when I upload .mo file into my site, all sidebar widgets disapear and default default content is displayed! As soon as you delete this file from server, you’ve got perfectly working site! What’s wrong, what could cause this strange behavior? I’ll be grateful for any clues.