WP won't update & install plugins since I translated the blog using Poedit

Few days ago, I tried to translate my blog (https://www.timemanagement.sk) to slovak language (sk_SK) using Poedit method described here https://forum.woothemes.com/topic.php?id=44498

Now, the theme (WooTheme-Canvas) is translated but I can not update any plugins or wordpress itself.
There is this update showing up on my dashborad:

You can update to WordPress 3.1.2–sk_SK automatically or download the package and install it manually:

Now the strange thing is that it never before showed the “sk_SK”. And when I click “Update Automatically” it freezes at “downloading…”.

I experience the same behaviour with plugins. Yesterday I tried to install W3 Total Cache plugin. I clicked ‘install’ it went to download the plugin (which usually takes less than few seconds) and it freezed at downloading. I waited for 5 minutes and nothing happend – not even any activity in the browser.

Well, obviously the problem is either with language setup in wp_config or chmod setting on my FTP. But I really don’t know what to do…. Please please could you help me? ??