I am running Ubuntu 10.04 64-bit, and when I attempt to start Nautilus from the command line, it does not appear -- although a PID is generated. As
sudo i can start Nautilus fine.
One note: I run e16 as the windows manager, so I do not use Nautilus to draw my desktop. However, even under this configuration, Nautilus used to run fine as a "regular" user.
The permissions for Nautilus are the same as the other packages in
/usr/bin. I believe this is a Gnome issue, but I'm fumbling at this point.