Sometime on Nov 29, Sameer D. Sahasrabuddhe assembled some asciibets to say:
I recently installed Nautilus on my Debian woody system ... but it seems to be missing a few pieces. It cannot render html pages on its own. Clicking on Help->User Manual, the html source of the page gets displayed instead of being renderred correctly.
You require the nautilus-mozilla plugin. Nautilus uses plugins to render different content-types.