I have  been testing successfuly for a couple of weeks with WSE 3.0.  Today
out of the clear blue, none of my projects work.  When the client executes
the Web Service, I get the following Error:

Message="System.Web.Services.Protocols.SoapHeaderException: Server
unavailable, please try later ---> System.ApplicationException: WSE842: The
service pipeline could not be created. --->
System.Configuration.ConfigurationErrorsException: WSE032: There was an error
loading the microsoft.web.services3 configuration section. --->
System.Configuration.ConfigurationErrorsException: The entry 'UsernameToken'
has already been added.\r\n   at
System.Configuration.BaseConfigurationRecord.EvaluateOne(String[] keys,
SectionInput input, Boolean isTrusted, FactoryRecord factoryRecord,
SectionRecord sectionRecord, Object parentResult)\r\n   at
System.Configuration.BaseConfigurationRecord.Evaluate(FactoryRecord
factoryRecord, SectionRecord sectionRecord, Object parentResult, Boolean
getLkg, Boolean getRuntimeObject, Object& result, Object&
resultRuntimeObject)\r\n   at
System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String
configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject,
Boolean requestIsHere, Object& result, Object& resultRuntimeObject)\r\n   at
System.Configuration.BaseConfigurationRecord.GetSection(String configKey,
Boolean getLkg, Boolean checkPermission)\r\n   at
System.Configuration.BaseConfigurationRecord.GetSection(String configKey)\r\n
 at System.Web.HttpContext.GetSection(String sectionName)\r\n   at
Microsoft.Web.Services3.Configuration.WebServicesConfiguration.get_Current()\r\n
 --- End of inner exception stack trace ---\r\n   at
Microsoft.Web.Services3.Configuration.WebServicesConfiguration.get_Current()\r\n
 at
Microsoft.Web.Services3.Configuration.WebServicesConfiguration.get_MessagingConfiguration()\r\n
 at
Microsoft.Web.Services3.WseProtocol.ModifyInitializedExtensions(PriorityGroup
group, SoapExtension[] extensions)\r\n   at
System.Web.Services.Protocols.SoapServerProtocol.Initialize()\r\n   --- End
of inner exception stack trace ---\r\n   --- End of inner exception stack
trace ---"
 
I've unistalled and reinstalled WSE 3.0 several times to no avail. I built a
new solution from scratch, but always end up with the same error as above.  
Any clues?