It seems that the configuration file /etc/dbus-1/system.d/bluetooth.conf is missing and it does not help to create one. Since the release of Knoppix V6.7.1 there is a new bluez package available in the Debian software package repository. When I installed this new package the configuration file bluetooth.conf was still missing in the directory /etc/dbus-1/system.d but it is included in the package.

After many attempts I found the following solution.

I used the Knoppix V6.7.1 CD with my USB Bluetooth dongle unplugged.

My first step was to download the package bluez_4.96-3 to my /home/knoppix directory.

I opened a terminal and extracted the package
Code:
dpkg -x /home/knoppix/bluez_4.96-3_i386.deb bluez
I installed the package
Code:
sudo dpkg -i /home/knoppix/bluez_4.96-3_i386.deb
I copied the configuration file bluetooth.conf.
Code:
sudo cp /home/knoppix/bluez/etc/dbus-1/system.d/bluetooth.conf /etc/dbus-1/system.d/
In the "Preferences" menu I selected "Desktop Session Settings". I selected "Bluetooth Manager" and "Policykit Authentication Agent" and closed the window.

In the terminal I issued
Code:
sudo init 2
I plugged my USB Bluetooth adaptor in. Then I issued
Code:
init 5
The graphical desktop environment started and the icon of the Bluetooth applet appeared in the system tray. The icon had got a red X. I disconnected my USB Bluetooth adapter and replugged it. Now the red X had disappeared and I was able to connect to my second computer.

Comments are always welcome.