Description:
Anytime a notification is posted by the nm-applet (I have one simple ethernet connection), it will freeze, producing a ghost window or a half. The applet will wait for it for a time and appear frozen as well during that time. Killing the notification-daemon removes the window. One can also disable notifications from the applet.
I don't know if it applies to other programs using notifications as I don't currently know any.

nm-applet produces
** (nm-applet:1862): WARNING **: Failed to show notification: 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.

sometimes I can see a similar message from libnotify:
libnotify-Message: GetCapabilities call failed: did not receive a replay.
Followed by a list of possible causes.

notification-daemon 0.4.0-4
networkmanager 0.8.1-1
network-manager-applet 0.8.1-2

Attaching a screen shot of the problem.

Steps to reproduce:
1. Start nm-applet
2. Trigger a notification (connect or disconnect)