There was an error starting the GNOME Settings Daemon.

Gnome通过startx启动时出现以下错误
There was an error starting the GNOME Settings Daemon.

Some things, such as themes, sounds, or background settings may not work correctly.

The last error message was:

Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

GNOME will still try to restart the Settings Daemon next time you log in.
启动之后，上下两则的Panel也会不定时地收起，然后再像自动隐藏那样的效果再出来，之后一些图标就没了，比如audacious和vuze。
找到以下方案试验后解决了：
http://ubuntuforums.org.sixxs.org/showthread.php?p=3639195
#6 Re: There was an error starting the Gnome Settings Daemon hi all,

I got this issue and I did some thing like this. (guessed and did), but it helped. It seems to be a crashing with the settings in your .gnome or .gnome2 or .gnome2_private or gcont, gcongd (I'm not sure which of it, so I removed all of them).

$ cd /home/xxx
$ ls -al
$ rm -rf .gnome .gnome2 .gnome2_private .gconf .gconfd
$ sudo reboot

Remove all the gnome related directories in /home/xxx and restart the computer. And in the login prompt set the session to Run X-Client script, or Gnome. That's it. Hope this will be helpful to you, but not sure whether it'll work on your end.