Version: (using KDE 4.4.2) OS: Linux Installed from: Ubuntu Packages I think it's because the socket in .kde/share/apps/nepomuk. Moving this folder to /tmp and symlink it make nepomuk work. Maybe it's enough to move the socket to .kde/socket-$hostname (can't try this because a symlink is deleted at the start).
SVN commit 1212382 by trueg: Use the socket dir for the Soprano communication socket to avoid problems with some file systems. BUG:238579 M +1 -1 storage.cpp WebSVN link: http://websvn.kde.org/?view=rev&revision=1212382