App.Config - Saving Configuration Error

[jordonkraft]

Hello,

I have been searching the net, MSDN, google groups and can't seem to
find anything about what is happening to me.

I have developed a application using VB.Net 2.0 and deploy it using
ClickOnce over a private network. I use AppSettings.Get ("") to
retrieve values form my app.config and I use
AppSettigns.Set tigns("").value = value to set values.

This has been working fine for a long time (10 months). All of a
sudden I am now coming across errors when I try to save the
configuration. This is how I save it:

Dim config As Configuration =
ConfigurationMa nager.OpenExeCo nfiguration(Con figurationUserL evel.None)

config.AppSetti ngs.Settings("" ).Value = newValue
'9-12 more settings set
' Save app.Config file
config.Save(Con figurationSaveM ode.Full, True)

When I call this method I get a "An extension of name
'clientCredenti als' already appears.. Extension names must be
unique... line 237"

At line 237 is information that is not in my normal app.Config file
when i develop. My Config file is less that 100 lines. It seems
the .net framework uses the app.Config for it's own settings also.

The 'clientCredenti als' is found in a section below my "AppSetting s"
in a tag
<system.service Model>
<extensions>
<behaviorExtens ions>
<add name='clientCre dentionsl.....>

I have no idea where this came form or why it would try to create a
send one or what but I have no idea what to do or proceed.

Any help would be appreciated,
Jordon