I am getting the below error when inserting a headline in org mode using
Ctrl-Enter or M-Enter
System : Ubuntu 10.04

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  looking-at(nil)
  (and (looking-at org-complex-heading-regexp) (match-beginning 4) (> p
(match-beginning 4)))
  (let ((p ...)) (goto-char (point-at-bol)) (and (looking-at
org-complex-heading-regexp) (match-beginning 4) (> p ...)))
  (save-excursion (let (...) (goto-char ...) (and ... ... ...)))
  (and (org-get-alist-option org-M-RET-may-split-line (quote headline))
(save-excursion (let ... ... ...)))
  (let ((split ...) tags pos) (cond (... ...)
(org-insert-heading-respect-content ... ... ... ... ...) (... ... ... ...
... ... ... ... ... ... ...) (t ... ...)))
  (if (and (bolp) (org-at-heading-p) (not eops) (or ... ...)) (open-line
(if blank 2 1)) (save-excursion (setq previous-pos ...) (end-of-line) (setq
hide-previous ...)) (and org-insert-heading-respect-content (save-excursion
...)) (let (... tags pos) (cond ... ... ... ...)))
  (let* ((empty-line-p nil) (eops ...) (org-insert-heading-respect-content
...) (level nil) (on-heading ...) (fix-level ...) (on-empty-line ...) (head
...) (blank-a ...) (blank ...) pos hide-previous previous-pos) (if (and ...
... ... ...) (open-line ...) (save-excursion ... ... ...) (and
org-insert-heading-respect-content ...) (let ... ...)) (insert head)
(just-one-space) (setq pos (point)) (end-of-line 1) (unless (= ... pos)
(just-one-space) (backward-delete-char 1)) (when (and
org-insert-heading-respect-content hide-previous) (save-excursion ... ...))
(when (and begn endn) (narrow-to-region ... ...)) (run-hooks (quote
org-insert-heading-hook)))
  (let (begn endn) (when (org-buffer-narrowed-p) (setq begn ... endn ...)
(widen)) (let* (... ... ... ... ... ... ... ... ... ... pos hide-previous
previous-pos) (if ... ... ... ... ...) (insert head) (just-one-space) (setq
pos ...) (end-of-line 1) (unless ... ... ...) (when ... ...) (when ... ...)
(run-hooks ...)))
  (cond ((or ... ...) (insert ... ...) (run-hooks ...)) ((or arg ... ...)
(let ... ... ...)))
  (let ((itemp ...)) (cond (... ... ...) (... ...)))
  org-insert-heading(nil nil)
  (let ((org-insert-heading-respect-content t)) (org-insert-heading arg
invisible-ok))
  org-insert-heading-respect-content(nil)
  call-interactively(org-insert-heading-respect-content nil nil)


Emacs  : GNU Emacs 23.1.1 (x86_64-pc-linux-gnu, GTK+ Version 2.20.1)
 of 2012-05-18 on batsu, modified by Debian
Package: Org-mode version 8.0.2 (release_8.0.2-68-g40635b @
/home/dsubramanian/.emacs.d/thirdparty/org-mode/lisp/)

current state:
==============
(setq
 org-log-done 'time
 org-speed-command-hook '(org-speed-command-default-hook
org-babel-speed-command-hook)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-tab-first-hook '(org-hide-block-toggle-maybe
org-src-native-tab-command-maybe
                      org-babel-hide-result-toggle-maybe
org-babel-header-arg-expand)
 org-src-mode-hook '(org-src-babel-configure-edit-buffer
org-src-mode-configure-edit-buffer)
 org-confirm-shell-link-function 'yes-or-no-p
 org-todo-keywords '(sequence "TODO" "INPROGRESS" "|" "DONE")
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers
                  org-cycle-hide-inline-tasks org-cycle-show-empty-lines
                  org-optimize-window-after-visibility-change)
 org-mode-hook '((lambda nil
                  (org-add-hook (quote change-major-mode-hook) (quote
org-show-block-all)
                   (quote append) (quote local))
                  )
                 #[nil "\300\301\302\303\304$\207"
                   [org-add-hook change-major-mode-hook
org-babel-show-result-all append
                    local]
                   5]
                 org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point
org-babel-execute-safely-maybe)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 org-insert-heading-respect-content t
 org-occur-hook '(org-first-headline-recenter)
 org-from-is-user-regexp nil
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 )