I think you are right and it may be the IDN portion and perhaps WordPress.COM dislikes processing
I've no idea why. ;)
If you are up to it and as an experiment, can you substitute your
WordPress Address (URL) and
Site Address (URL) from
This is the ASCII version that I retrieved via http://www.dns.pl/cgi-bin/en_idntranslator.pl
You can do this on a temporary basis for testing by making a backup copy of your
wp-config.php file (call it wp-config-SAVE.php`) and in the original file add these two lines.
That way if anything goes wrong then all you have to do it restore the saved backup copy of
Let us know if you are willing to try that and if that works.