[h-e-w] backward-kill-word in minibuffer

[Albert, Jürgen]

Hello,

I am used to work with backward-kill-word (C-del) within the minibuffer
especially when I do find-file (backward-kill-word removes one directory
hierarchy from my path). 
Emacs 20.7 did a very good job by preventing my to walk into the "Find
file:" prompt at the mini buffer. 
Emacs 21.1 do not stop at the "Find file",  only saying "Text is read-only:
#<buffer *Minibuf-1*>" and my curson is positioned within the "Find file:".

Any ideas?
juergen