Item has already been added. Key in dictionary:"winbootdir" Key being added: "winbootdir"

[microsoft]

When I create a instance of web services proxy in winform, I get the
exception.

Stack Trace:

System.ArgumentException: Item has already been added. Key in
dictionary:"winbootdir" Key being added: "winbootdir"
at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean
add)
at System.Collections.Hashtable.Add(Object key, Object value)
at System.Collections.Specialized.StringDictionary.Add(String key, String
value)
at System.CodeDom.Compiler.Executor.ExecWaitWithCapture(IntPtr userToken,
String cmd, String currentDir, TempFileCollection tempFiles, String&
outputName, String& errorName, String trueCmdLine)
at System.CodeDom.Compiler.CodeCompiler.Compile(CompilerParameters
options, String compilerDirectory, String compilerExe, String arguments,
String& outputFile, Int32& nativeReturnValue, String trueArgs)
at System.CodeDom.Compiler.CodeCompiler.FromFileBatch(CompilerParameters
options, String[] fileNames)
at
System.CodeDom.Compiler.CodeCompiler.FromSourceBatch(CompilerParameters
options, String[] sources)
at System.CodeDom.Compiler.CodeCompiler.FromSource(CompilerParameters
options, String source)
at
System.CodeDom.Compiler.CodeCompiler.System.CodeDom.Compiler.ICodeCompiler.C
ompileAssemblyFromSource(CompilerParameters options, String source)
at System.Xml.Serialization.Compiler.Compile()
at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings)
at System.Xml.Serialization.XmlSerializer.FromMappings(XmlMapping[]
mappings)
at System.Web.Services.Protocols.SoapClientType..ctor(Type type)
at System.Web.Services.Protocols.SoapHttpClientProtocol..ctor()
at Shenjsoft.Dzsb.Net.localhost.CommonService..ctor()