Probably your font is not able to display the "special" (e.g., usually, non-English) characters, Do those "squares" contain a pair of small, hard-to-read, hexadecimal characters? If so, you are probably trying to display a graphical font (e.g., Chinese, Japanese, etc.)
Install some non-European fonts and see what you get.
Or, direct your output to a file, and use hexdump to see what's in it.
Of course, this begs the question of "Why are non-European fonts being selected?" Do you have a language preference set in "Preferences->Region and Accessibility?"