[Zope-CMF] Error on Install of Plone 1.3

[Slade Mrs A]

I've just downloaded and tried to install the latest development version of
Plone (Plone 0.9.9 - Bola), however, when I restart Zope I get the following
error:  
Import Traceback
Traceback (most recent call last):
  File "C:\PROGRA~1\Zope\lib\python\OFS\Application.py", line 531, in
import_product
    product=__import__(pname, global_dict, global_dict, silly)
  File "C:\Program Files\Zope\lib\python\Products\CMFPlone\__init__.py",
line 4, in ?
    import PloneFolder, PortalFactory
  File "C:\Program
Files\Zope\lib\python\Products\CMFPlone\PortalFactory.py", line 18, in ?
    from Extensions.Upgrade import normalize_tabs
ImportError: No module named Extensions.Upgrade

I saw reference to this in a message on 4 June
(http://zope.nipltd.com/public/lists/ptk-archive.nsf/13efd285960dfebf802568c
100635fee/e10e924ad39c7b6780256bce006e2198?OpenDocument), and have applied
what was suggested there (made sure I'm using CMF 1.3b1).  However, still
having the problem!  Zope version 2.5.1 on Windows.

Any suggestions?
Thanks,
April

April Slade
Web Projects Officer
Information Services
Cranfield University (RMCS)
Shrivenham
SWINDON
SN6 8LA
 
a.slade@rmcs.cranfield.ac.uk