I must be doing something wrong. This is my first Debian install.
When I try to log on as root, Debian 6 gives the message that
the pass word is invalid. I know the root pass word. I installed
the system. So I eventually give up and log on as an ordinary
user. Then I start a terminal and using su, log on as root using
the very same root pass word. This works. Well, thinks I, we
are now getting somewhere. But I'm wrong. When I try to change
user to root, the root pass word is rejected as invalid.
What can I do to log on as root at bootup in Debian 6 ?
There is no security issue. This particular machine is not on
the internet and I'm the only one who uses it.

Hi,

by default X login/display managers are configured to not allow root login in Debian. You should be able to log in to a console as root.

If you really want to log into X as root, you will need to configure your display manager. Eg edit /etc/gdm/gdm.conf

Note that running a full X session as root is generally a *very* bad idea.

Evo2.

Which is the correct way to do it. There is no reason to log in to an X session as root.

Well, OK. I guess root is not for me on Debian.
Them Debian experts know best. After all, who am
I to want to be root ? Just the guy who owns the
computer and installed the OS, pays for the Internet
cable, runs the computer... A nobody. So be it.
This thread is solved.

My first comment is to switch to Slackware! root access out of the box! (BTW, I like Debian and I am using Debian right now on this particular laptop)

In Debian do this:

Edit this file as root: /etc/pam.d/gdm3

Comment out this line with a hash:
#auth required pam_succeed_if.so user != root quiet_success

You can now select Other User at the GUI login and login as root. (might need to reboot first)

You can also switch to a console (Ctrl+Alt+F1) kill gdm and then run "startx" as root.

Correct.
Correct again.
To run a command as root
enter the root password, enter the commands, then:
To run a gui application as root
enter the root password.

No one says you can't do it. It's simply not recommended to run an entire desktop under root. It's not just a Debian thing either. There are apps that will warn you or even refuse to run as root. Even M$ has finally figured this out.