I had a similiar problem when I installed navit from the Maemo repository. I downloaded an OSM-Bin map, installed the lib for the icons and enabled the osm mapset. Navit started without any error but no map was shown. I forgot to disable the mapset for userdefined maps. After having done that the map finally showed.
Maybe it'll help you as well?

Cheers,
britschler

ps: anyony knows where to find this png?
navit:displayitem_draw:failed to load icon 'traffic_signals.png'