Strange JKVC characters at the login box

[Alfred Vahau]

Hi,
The firefox browser is set to load the online library catalogue
which it loads automatically on first bootup. When a user closes
the browser, a login prompt is presented for the user to login.
The language used is English.

I have been monitoring how users, mostly students react to this
non-Windows PC. Today I found that the characters I typed in
at the login prompt (username and password) appeared as JKVC
characters. Obviously these were not recognized and so  the system
died me access.

This is an entirely new problem which I had not encountered or
anticipated since deploying the Ubuntu-based catalog browser on
September 1st.

I have checked the Session and Language settings on the Gnome
interface but there is nothing to suggest to me how to get the English
characters back.

I did an Alt+F7 to get the console and shutdown the system.
The characters presented at the console were in English.

I have not ruled out the possibility of tampering with the system. The 
library
project is the first of several opensource projects that I am initiating
in an otherwise MS computing environment in my institution using Ubuntu 
linux.

How were the characters changed from English to JKVC and what
do I need to do get the characters back to English at the login prompt?
The BIOS setup is password protected, the CD and the A-drives are
disabled and the screen is password protected.

Alfred Vahau