I had the same problem and the only way I made it work is with a Domain
Account with a Custom Principal Name using SetSPN.exe utility. I reported
this issue (does not work WSE 3.0 + XP-SP2 with ASPNET account) to
Microsoft-PSS in December 2005 and currently they have no reached any
solution about it (how to make it work with ASPNET account). May be WSE 3.0
documentation is wrong. Currently, they passed this issue to WSE 3.0 product
group.
BTW, with Windows Server 2003 everything works great by default (using
Network Services account for IIS process pool).
So, to sum up, yes, currently, over Windows XP-SP2, WSE 3.0-Kerberos does
not work with ASPNET account. The only way is using a Domain account with a
custom pricipal name (using Setspn.exe utility in a DC).

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Software Architect
[Microsoft MVP - XML Web Services]
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Renacimiento
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> Hi Martin:
> I using Kerberos token.
[quoted text clipped - 6 lines]
> >
> > Martin
Shankar - 25 Jun 2007 20:25 GMT
Hi,
I'm trying to get a Kerberos token from a windows 2003 server using C#. Can
you guys share your code?
Regards,
Shankar
> I had the same problem and the only way I made it work is with a Domain
> Account with a Custom Principal Name using SetSPN.exe utility. I reported
[quoted text clipped - 21 lines]
> > >
> > > Martin