File mode specification error: (invalid-regexp "Invalid regular expression")

[Roberto Bernetti]

Hi 
I'm using opensuse 10.2 with GNU Emacs 21.3.1
emacs the following line working in in my gnu-emacs-custom file:
--------------------------
;; Modifying alist
(setq auto-mode-alist
      (cons '("\\.max" . maxima-mode) auto-mode-alist) )
(setq auto-mode-alist
      (cons '("\\.m$" . octave-mode) auto-mode-alist))
(setq auto-mode-alist
      (cons '("\\_dbg$" . makefile-mode) auto-mode-alist))
(setq auto-mode-alist
      (cons '("\\.fi$" . fortran-mode) auto-mode-alist))
(setq auto-mode-alist
      (cons '(".gnu-emacs-custom$" . lisp-mode) auto-mode-alist))
(setq auto-mode-alist
     (cons '("smb\\.conf$" . smb-mode) auto-mode-alist))
(setq auto-mode-alist
     (cons '("\\.mc$" . maxima-mode) auto-mode-alist))
(setq auto-mode-alist
     (cons '("\\.mx$" . maxima-mode) auto-mode-alist))

no more work in opensuse 11.0 with GNU Emacs 22.2.1.
I get the following error loading any file i the previous list:

File mode specification error: (invalid-regexp "Invalid regular expression")

browsing the mailing list I changed to 

(add-to-list 'auto-mode-alist '("\\.fi$" . fortran-mode))

but for the string:
(add-to-list 'auto-mode-alist '("\\_dbg$" . makefile-mode))
I still get the previous error.

P.S. I'm not in the list.
-- 
Saluti
Roberto