While inserting an annotation, I used ispell to check a word, it worked
several times (I think) and then subsequently, the debugger was entered
after ispell's correct spelling message:

Debugger entered--Lisp error: (error "Attempt to split minibuffer window")
  split-window(nil 2)
  ispell-overlay-window(2)
  ispell-show-choices(2 #<marker at 125 in  *Minibuf-1*>)
  ispell-command-loop(("component" "components" "compliant" "complainant" "complaint" "component's" "compound" "competent") nil "componant" #<marker at 116 in  *Minibuf-1*> #<marker at 125 in  *Minibuf-1*>)
  byte-code("AA@AAA@@	\n%ć" [poss start end replace ispell-command-loop] 6)
  ispell-word(nil nil nil t)
  call-interactively(ispell-word nil nil)
  read-string("text: ")
  (let ((text ...)) (if (equal text "") (message "Empty annotations are not inserted.") (ipa-create-overlay ... text) (if ... ... ...)))
  ipa-insert()
  call-interactively(ipa-insert t nil)
  execute-extended-command(nil)
  call-interactively(execute-extended-command nil nil)

After doing `q' to exit the debugger, the annotation I was typing
vanished, not to be found in .ipa~.

Next, I did emacs -q and while the text of my annotation didn't
vanish, the attempt to use ispell resulted in the same `Attempt to
split minibuffer window' error.

This in,

GNU Emacs 23.0.93.1 (i686-pc-linux-gnu, GTK+ Version 2.14.4) of
2009-05-13 on g41r2f1