I'm having the exact same problem. Getting the same error from mail.app.
I cannot save any preferences: Cannot change desktop pic, dock changes not persisted, widget changes not persisted,cannot change rss feeds in New Fire. My Mobile Me Calendar sync is getting a bit wonky with it not deleting items, this may or may not be the same problem.
Basically my machine is stuck the way it is now and now amount of yelling will make it change.
I've opened the file ~/Library/Prefrences/com.apple.desktop.plist and made a trivial change, but when I try to save the change it says I don't have permission. When I look at the permissions on the file (using Get Info), it says I have Read & Write and Everyone has No Access.
When I ran Repair / Verify permissions I gave some warnings about ACL's on the Application and Preferences directory that were not expected. This is what it said...
ACL found but not expected on "private/var/log".
ACL found but not expected on "Applications".
ACL found but not expected on "Library".
I found some info on the web and deleted them. I just checked and they are back, here is part of the listing from ~/Library using "ls -leh"
drwx------+ 196 aaron staff 6.5K 15 Jan 22:48 Preferences
0: group:everyone deny add
file,delete,add_subdirectory,deletechild,writeattr,writeextattr,chown
1: group:everyone deny delete
drwx------+ 2 aaron staff 68B 15 Mar 2008 Screen Savers
0: group:everyone deny delete
drwx------+ 2 aaron staff 68B 15 Mar 2008 Sounds
0: group:everyone deny delete
There are 15 "1: group:everyone deny delete" ACL's in ~/Library. Last time there were only the 3 above which I deleted.
Looking in the preferences folder only a few files have been modified today. First are the files for my stinking 3G mobile net connection, and others are half a dozed apple preferences inside the "By Hosts" directory.
The biggest change I've made to my mac in the last few weeks is use the 3G modem. The SW was already installed but I did not use it.
Any help appreciated as this is a real pain and I dont want to re-install 5 days before travelling for a month.
Cheers
Aaron
Message was edited by: Aaron Morton