Newbie password problem(s)

[Richard Owlett <rowlett@cloud85.net>]

I've been doing a series of Debian installs over the last 
several months.
YES. There are easier ways to do things. *BUT* my purpose is 
_educational_ rather than "efficiency" ;)

I have a history of problems with the root password not 
being recognized.

If the problem *DOES* occur on a  individual install 
iteration , it *WILL* occur on *EVERY* cold boot and *EVERY* 
time a root password is required.
If the problem *DOESN'T* occur on a  individual install 
iteration , it *WILL NEVER* occur on *ANY* cold boot and 
*ANY* time a root password is required.

Whether or not the problem appears is independent of:
   install media - LiveCD or purchased 8 DVD set
  target machine - Lenovo ThinkPad or Lenovo desktop

On  reinstall the problem may or may not occur independent 
of previous condition.

The current problem iteration:
A minimum CLI install on the desktop machine.
A successful boot which accepted my user name and password.
Attempted to use su command, would not accept either password.
Successful "apt-get install gdm3" using user password.
Reboot resulted in expected GUI.
Could not access either "Root Terminal" nor "Synaptic" from 
menu - password not accepted.

When rebooting into "Rescue Mode", the last two lines 
displayed are:
sulogin: root account is locked, starting shell
root@localhost:~#

At this point I'm allowed to do "apt-get install xyz" - no 
password required.


Comments, questions, suggestions?????