Comment 117 for bug 25931

I had exactly the same after few weeks of use of a fresh Gutsy install, with apparently no reason.
I tried everything listed here and elsewhere:
- concurrency set to "none" (this never changed)
- reordered /etc/rc2.d/ levels (S12dbus and S13hal)
- installed/reinstalled packages
- reconfigured all packages

but still dbus was up, hald refused to start.
Then I checked:

less /etc/default/hal

and output was

DAEMON_OPTS=

Then I changed it with:

sudo nano /etc/default/hal

into:
DAEMON_OPTS=--retain-privileges

then save, and rebooted.
I'm not sure if the above tried procedures were somehow useful or just wasted time, but the problem is now solved.

Hope this helps.
-E-