That's strange. I don't have any opera or font-related hacks. For me it happens also with mono downloads page http://www.mono-project.com/Downloads . Both pages work the same for a long time for me. Just thought they contain some weird html stuff. But if you can see it properly then it is something different. Tried to move /home/user/.opera but after automatic re-creation it still shows blocks. Tried both optimized/non-optimized views various zoom levels, tried also various encodings and it still happens. As for fonts I have only additional Vera fonts which come with osso-xterm.