i hope not. i get that on quite a few gtk apps, but they all fallback to a working font. what font does calibre default to so i can make sure i have it installed?
#Edit: okay so you were right
It seems that if you set a strange font (clearlyui glyphs for me) in the gnome appearence for application font, it freaks every pango app out. most will default to another font to recover. calibre does not. I fixed it, though it would be awesome if calibre would fall back on a sans font automagically. anyway, thanks for the help