Folding stops working

[Michael Hohmuth <Michael.Hohmuth@amd.com>]

Hi,

I recently started using Org extensively, and I'm a very happy user --
except for one annoying problem:

Every now and then, folding just stops working.  Pressing TAB or (my
equivalent of) S-TAB still displays messages such as "OVERVIEW" in the
mode line, but everything always gets expanded instead of folded.
(The exception being my :PROPERTIES: drawers, which expand in
OVERVIEW mode but close in the SHOW ALL and CONTENTS modes.)

Even killing the buffer and reloading the file doesn't help.  I need
to shut down and reboot Emacs in order to get back to normal.

Could you please help me diagnose and fix the problem?  I'm using GNU
Emacs 22.1.1 and Org-mode 6.13a.

Thanks,
Michael
-- 
Michael Hohmuth, AMD Operating System Research Center, Dresden, Germany
michael.hohmuth@amd.com, www.amd64.org