If you cannot log in through command prompt (putty, terminal, console [Ctrl+Alt+F2]) as root then you may have an issue with the original input of the password. In this case you would need to restart the server in 'single' mode and reset the password.

Reset root password.

If you can log in through command line but not in the interface then there may be something that is improper with you password that is being translated wrong by the form. For example, percents are bad if followed by an ascii hexidecimal number (and yes, I know this is not what you describe).

I don't think that's the problem here, but if I can't log in, how can I run sudo?

Yes, I know what the regex group means. I was just checking as I'd found the link.

Your http session will be interpreted by the workstation's key mappings but the console will be interpreted by ClearOS's keyboard map. Have a look at this post for checking and possibly changing the locale.

Nick,

My root password is only [a-zA-Z0-9]+. I assume you know what that means. ...Examples: ebruer75hdgfh , gu475uifhdgte4ygb, r4y5ghjfhr . My real password has 8 letters and 4 digits. It has no embedded words over 1 character in length in any language (thereby defeating a dictionary attack). The hardware is a Dell Optiplex with a standard keyboard.

May I reiterate: My HTTP 'root' log-in works, but the same password is rejected by the red "Administrator Password" box at the local console at the end of the boot, and is rejected by a secondary console (opened by pressing Alt-F2) even when I attempt to log in as 'root'. They have never worked, but the User Guide skips over it as though, if the server successfully boots, then X-windows is running. Ah, but first you must log in. That's what I've never been able to do.

Valid password rules can be found here. Does your system have a non-English keyboard layout? I can't even remember where this is set for the console.

Try this;
http://linuxconfig.org/recover-reset-forgotten-linux-root-password

My HTTP log-in is:
User = root
Password (regexp pattern) = [A-Za-z0-9]+

This must be different from User = Administrator.

What I've tried:
When boot is complete, I'm presented a red box asking "Administrator's password:" Nothing works.
If I use Alt-F2 to open an auxiliary console and attempt to log in as root and use the same (successful) password as my HTTP 'root' log-in, that password gets rejected too.

I've been limping along for years like this because I didn't have anyone I could ask and there wasn't anywhere on the Internet to go to ask for help. If you will help me, I'll be forever grateful.

Regards, Mark.

Do you use any special characters in your password? There are some limitations, but I cannot remember what they are.