changing key behavior

[Alex Dean]

I'm not sure what I did, but I've apparently changed a setting one of  
my Debian machines which is making it difficult to edit text.

  - vi : In insert mode, I cannot use backspace to erase any existing  
text.  I can erase what I have typed during my current insert, but  
the erased characters do not actually disappear until I have either  
typed something else over them, or I have switched to command mode.   
(Before this change, backspace worked to delete any text in the  
document, and the deleted characters disappeared immediately.)  Any  
text that was in the document before I started my insert cannot be  
altered via backspace.  I have to go to command mode and press x to  
delete anything.
  - pico : backspace deletes what is to the right of the cursor, not  
what is to the left as it used to do.
  - from a shell : backspace works as expected.

These symptoms are system-wide.  The affect emote (ssh) and local  
logins for all user accounts.  What could be the cause of this?

thanks,
alex
.