Wow, I changed default browser from Chrome to IE and then it worked, thanks
I always thought this file is connected to something like acrobat reader :P
Oh, and now I came back to Chrome as default and I can still open file, brilliant!
Ok, so now when this is solved I have a question: Some time ago I saw here a mod, which let you write your own patrol notes while in-game. If you know what is this mod and could point me to thread with it, I would be glad because I don't remember who made it and how is it called