WSUS install fails while configuring IIS

I am having issues installing WSUS on a Windows 2003 member server. The
application server role has been defined and BITS 2.0 has been installed.
This server is fully patched except for SP1.

I receive this error when installing WSUS:

Microsoft Windows Server Update Services could not configure the
administration site or some of the virtual directories. For more information,
see the Setup log "C:\Program Files\Update
Services\LogFiles\WSUSSetup_050608_1915.log".

Contents of the log file:

2005-06-08 19:21:21 Success CustomActions.Dll .Net framework path:
C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322
2005-06-08 19:21:29 Success CustomActions.Dll Creating WSUS
Administrators user group
2005-06-08 19:21:29 Success CustomActions.Dll Successfully created WSUS
Administrators user group
2005-06-08 19:22:59 Success CustomActions.Dll Successfully configured
the database
2005-06-08 19:23:01 Info IISCustomAction Performing Setup Action,
Command /Install
2005-06-08 19:23:45 Error IISCustomAction Command /Install
FailedSystem.InvalidCastException: Specified cast is not valid.
2005-06-08 19:23:45 Error IISCustomAction at
Microsoft.UpdateServices.Setup.IisWebService.ApplyConfig(IIisMetabaseDriver
metabaseDriver, IisMetabaseObject target)
2005-06-08 19:23:45 Error IISCustomAction at
Microsoft.UpdateServices.Setup.IisMetabaseObject.Apply(IIisMetabaseDriver
metabaseDriver)
2005-06-08 19:23:45 Error IISCustomAction at
Microsoft.UpdateServices.Setup.IisConfig.ApplyConfig(IIisMetabaseDriver
metabaseDriver, Boolean upgrading, Boolean& siteCreated)
2005-06-08 19:23:45 Error IISCustomAction at
Microsoft.UpdateServices.Setup.IisCustomAction.Install(String
installRevision, String configFilePath, String webSiteName, String
newWebSiteBinding, String newWebSiteRootPath, String[] rootPaths)
2005-06-08 19:23:45 Error IISCustomAction at
Microsoft.UpdateServices.Setup.MainClass.Install()
2005-06-08 19:23:45 Error IISCustomAction at
Microsoft.UpdateServices.Setup.MainClass.PerformSetupAction()
2005-06-08 19:24:04 Info IISCustomAction Performing Setup Action,
Command /Rollback
2005-06-08 19:24:04 Info IISCustomAction Command /Rollback Succeeded


Any ideas? I have re-installed the applicaton server role and enabled
ASP.NET to no avail.

Nick,

What language is the OS and any other infomation about the system? Are
installing to the default web site or specifing? What Language of WSUS are
attemping to install?