Configuration Wizard can't find SharePoint sectiongroup in WEBCONFIG.ACCSRV.XML

When trying to run the Configuration Wizard it fails on Step 8 with:

Failed to install the application content files.

An exception of type System.IO.InvalidDataException was thrown. Additional exception information: The web configuration file, C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\config\WEBCONFIG.ACCSRV.XML, does not have element "configuration/configSections/sectionGroup[@name='SharePoint']" or it is invalid.

What should I add to the file? It appears that it needs to be a <Add Path=""> statement; but what the entire parameter set is I haven't located after a day of searching.

Marc