[Orgmode] org-mode crashes with this stacktrace:

[Tudor Gabriel]

I'm trying to learn org-mode. 
Each time I try to open agenda buffer, I get that error.

If I can provide any additional info, please, don't hesitate to ask.

Debugger entered--Lisp error: (wrong-type-argument listp "|")
  org-set-regexps-and-options()
  org-mode()
  set-auto-mode-0(org-mode nil)
  set-auto-mode()
  normal-mode(t)
  after-find-file(nil t)
  find-file-noselect-1(#<buffer hobby.org> "~/org/hobby.org" nil nil
"~/org/hobby.org" (174122 2053))
  find-file-noselect("/home/tudor/org/hobby.org")
  org-get-agenda-file-buffer("/home/tudor/org/hobby.org")
  org-prepare-agenda-buffers(("/home/tudor/org/hobby.org"
"/home/tudor/org/tasks.org" "/home/tudor/org/ardendo.org"
"/home/tudor/org/home.org"))
  org-prepare-agenda("Day/Week")
  org-agenda-list(nil)
  call-interactively(org-agenda-list)
  byte-code("Æ ÇÆÈÉ   \"\"pÊË address@hidden>
  org-agenda(nil)
  call-interactively(org-agenda nil nil)