[Setup] Install error: string index out of range

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Plone 2.1.2 running on Zope 2.8.5
Adding a Plone site does not work and gives the following error:-

Error Type: IndexError
Error Value: string index out of range

Traceback (innermost last):

    * Module ZPublisher.Publish, line 113, in publish
    * Module ZPublisher.mapply, line 88, in mapply
    * Module ZPublisher.Publish, line 40, in call_object
    * Module Products.CMFPlone.Portal, line 465, in manage_addSite
    * Module Products.CMFPlone.Portal, line 437, in create
    * Module Products.CMFPlone.Portal, line 394, in setupPlone
    * Module Products.CMFPlone.MigrationTool, line 274, in upgrade
    * Module Products.CMFPlone.MigrationTool, line 371, in _upgrade
    * Module Products.CMFPlone.migrations.v2_1.alphas, line 61, in
two05_alpha1
    * Module Products.CMFPlone.migrations.v2_1.alphas, line 267, in
installArchetypes
    * Module Products.CMFPlone.migrations.migration_util, line 79, in
installOrReinstallProduct
    * Module Products.CMFQuickInstallerTool.QuickInstallerTool, line 320,
in installProduct
      __traceback_info__: ('MimetypesRegistry',)
    * Module Products.ExternalMethod.ExternalMethod, line 225, in __call__
      __traceback_info__: ((<PloneSite at /geprojectdatabase>,), {}, None)
    * Module
c:\Zope-Instance4\Products\MimetypesRegistry\Extensions\Install.py,
line 24, in install
    * Module Products.CMFCore.utils, line 627, in manage_addTool
    * Module Products.MimetypesRegistry.MimeTypesRegistry, line 99, in
__init__
    * Module Products.MimetypesRegistry.mime_types, line 13, in initialize
    * Module Products.MimetypesRegistry.mime_types.py_mimetypes, line 44,
in initialize

IndexError: string index out of range

Thanks
Millie