Do you have, or have you had, KDE installed? It messes with Gnome's font settings in ~/.fonts (iirc). If you have that file could you try removing it and restarting Gnome? The problem is gone on my Feisty install, including with Abiword.
However, although its a separate issue, I really think this problem with KDE messing up Gnome's fonts needs fixing.
Do you have, or have you had, KDE installed? It messes with Gnome's font settings in ~/.fonts (iirc). If you have that file could you try removing it and restarting Gnome? The problem is gone on my Feisty install, including with Abiword.
However, although its a separate issue, I really think this problem with KDE messing up Gnome's fonts needs fixing.