Recent versions of Debian Squeeze with an LXDE desktop generate an error when you try to make and save changes using obconf. The default theme is Clearlooks, and it’s too close to Ubuntu for my liking, I prefer Onyx. This has been fixed in updated packages, but they have not yet made their way into the testing repositories. Here’s how I fixed it

1. Open your sources file and add (or uncomment) the Debian testing repositories

sudo leafpad /etc/apt/sou*

and then add or uncomment

deb unstable main contrib non-free
deb-src unstable main contrib non-free

2. The update your LXDE desktop with the LXDE packages from testing

apt-get update
apt-get -t unstable install lxde

3. Make sure you install the lxde meta-package and not just lxsession as it will generate an error and not let you boot into a working desktop (trust me).

4. Comment-out or remove the testing repositories and run

apt-get update

to ensure that you don’t accidentally upgrade to Sid the next time you run a system update. You should be able to make and save changes in obconf now.