nautilus does not start after login

Binary package hint: nautilus

Ubuntu 10.04 Lucid Lynx
nautilus 1:2.30.0-0ubuntu4
compiz: 1:0.8.4-0ubuntu15
emerald: 0.7.2-0ubuntu4
nvidia-current: 195.36.15-0ubuntu2 (on 9300M chipset)

On my current setup (compiz activated, using emerald as window decorator), nautilis won't start after login. The desktop icons are displayed neither. A manual run in a terminal gives this result:

> $ nautilus
> Initializing nautilus-gdu extension
> Initializing nautilus-open-terminal extension

If I disable emerald and compiz, the icons won't show up, too.

Another interesting feature is the behaviour on opening places/favourites:

> Speicherort »file:///home/dmke/repositories« konnte nicht angezeigt werden
> Es wurde keine Anwendung gefunden, die diese Datei verarbeiten kann

(I don't know the exact translation, but obviously there is no url handler for »file://«...)