I have a Debian Lenny desktop PC (64-bit), and a Debian Lenny laptop (32-bit). The problem occurs for me only on the laptop in the same way as given by http://www.linuxquestions.org/questions/debian-26/gnome-settings-daemon-error-743425/#post3636199so there are others that are seeing this as well. Both desktop and laptop systems are kept up to date for Debian updates.
One serious aspect of this is that the dialog that shows up does not present sufficient info to allow the user to triage the problem themselves (i.e., the message is too vague to be of any use). My laptop is a IBM Thinkpad R51. "About Gnome" for my laptop exhibiting the problem shows: Version: 2.26.1 Build Date: 04/14/2009 Thanks, Brent P.S., Keep up the good work! I am otherwise quite happy with the Debian Linux distribution!