Membership credential verification failed...

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Hi all,

I have a problem with a webservice using WSE 3.0. I have a web-service which
pulls data from a database and a client which pulls the data from the
webservice. I have created a user using the web admin tool and everything
works fine. However, I need to run the client application as a windows
service and this is where the fun begins. Whenever I run the windows service
I am unable to log into the webservice and subsequent calls from the client
application (i.e. the same code as the windows service but running as a
stand-alone app) fail with the same error. In the event log before the first
failure I get an ASP.NET webevent stating "Membership credential verification
failed".

What's really strange is that if I delete the user from the database (and
re-create them with the same credentials), the client application will work
again (until the windows-service is re-run).

I have checked the application name in the membership provider as this seems
to be the general answer for this issue but this is ok. The fact that it
works when running as an application suggests that everything is fine. I
suspect that it is something to do with the account that the service is
running in (which is Local System). I don't see how that should effect the
webservice though (especially when they are running on different machines)

Any help would be greatly appreciated, I have a tight deadline for this and
have already wasted far too much time trying to find a resolution.

Neil.