I installed Lubuntu 15.04 Vivid last week, making the first step away from Windows for me.
I am running Firefox 38.0 (Mozilla Fifefox for Ubuntu canonical - 1.0). In Windows 7, when I loaded pages with non-Latin/special characters like Japanese Kanji and Korean, they were displayed correctly, but now Firefox seems to have a problem displaying them; they appear like boxes with letters and numbers in them.
The only advice I've found was to change the Settings > content > Allow pages to choose their own fonts, instead of my selections above to true, but that was already set.
What else can I try?