Comment 5 for bug 877143

Same here after upgrading from 11.04 to 11.10.
The ticket 879793 says that the behavior is a random phenomena, which it is not for me. gnome-settings-daemon always dies when the session is started. The .xession-errors contains two errors.

(gnome-settings-daemon:1835): Gdk-WARNING **: The program 'gnome-settings-daemon' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadMatch (invalid parameter attributes)'.
  (Details: serial 505 error_code 8 request_code 147 minor_code 22)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

(gnome-settings-daemon:1856): Gdk-WARNING **: The program 'gnome-settings-daemon' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadMatch (invalid parameter attributes)'.
  (Details: serial 521 error_code 8 request_code 147 minor_code 22)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

There are also warnings about non-existent icons:
WARN 2011-10-30 17:27:56 unity.iconloader IconLoader.cpp:509 Unable to load contents of file:///usr/share/icons/unity-icon-theme/places/svg/category-installed.svg: Error opening file: No such file or directory
WARN 2011-10-30 17:27:56 unity.iconloader IconLoader.cpp:509 Unable to load contents of file:///usr/share/icons/unity-icon-theme/places/svg/category-available.svg: Error opening file: No such file or directory