Unsusal Exception

[Lucky]

hi guys!
i've come across one error that i'm not able to understand.

Scenerio:

i'm using a file upload control to upload a file.
<input type="file" id="tbFile" class="InputField" runat="server"
NAME="tbFile"/>

when i'm selecting a file and click on "upload" button it gives me this
error that i'm not able to understand.

Error: 29-09-2006 12:38:54 [] [Global] : Application error occured

The file '/ClientWebService/client.asmx' does not exist.

Exception[System.Web.HttpException ]

at System.Web.UI.Util.CheckVirtualFileExists(VirtualPath
virtualPath)

at
System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath
virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean
allowBuildInPrecompile)

at
System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext
context, VirtualPath virtualPath, Boolean noBuild, Boolean
allowCrossApp, Boolean allowBuildInPrecompile)

at
System.Web.Compilation.BuildManager.GetVPathBuildResult(HttpContext
context, VirtualPath virtualPath)

at System.Web.UI.WebServiceParser.GetCompiledType(String inputFile,
HttpContext context)

at
System.Web.Services.Protocols.WebServiceHandlerFactory.GetHandler(HttpContext
context, String verb, String url, String filePath)

at System.Web.HttpApplication.MapHttpHandler(HttpContext context,
String requestType, VirtualPath path, String pathTranslated, Boolean
useAppConfig)

at
System.Web.HttpApplication.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()

at System.Web.HttpApplication.ExecuteStep(IExecutionStep step,
Boolean& completedSynchronously)
-------------------------------------------------------------------------------------------------------------------------------------

The file it is talking about and the directory, i'm not using in my
project, neither they exists anywhere in my project, neither exists
anywhere on my pc. i've no idea how come it is giving me this error.

can anyone tell me what u could be the problem here? coz i'm not able
to understand the error.

Tools:

asp.net 2.0 and IIS 6.0

thanks,
Lucky