100% CPU usage becoz of System.Configuration.ConfigurationExceptio

[Guest]

When I'm running my ASP.NET application, system throws the following
exception. Although page is displayed properly but this exception is thrown
internally.
And also when I'm doing load testing for this page by using ACT with the
scenario of 50 users, I find that CPU usage is 100%. (w3wp.exe takes 100% CPU
usage.)
Please help me.

Error Exception ::

"System.Configuration.ConfigurationException: It is an error to use a
section registered as allowDefinition='MachineToApplication' beyond
application level.
This error can be caused by a virtual directory not being configured as an
application in IIS. (D:\Project_Work\Project_Name\web.config line 266)
at System.Web.Configuration.HttpConfigurationSystem.CacheLookup(String
vpath)
at System.Web.Configuration.HttpConfigurationSystem.ComposeConfig(String
reqPath, IHttpMapPath configmap)
at System.Web.HttpContext.GetCompleteConfigRecord(String reqpath,
IHttpMapPath configmap)
at System.Web.HttpContext.GetCompleteConfig()
at System.Web.HttpContext.GetConfig(String name)
at System.Web.ImpersonationData.Init(Boolean appLevel, Boolean
throwOnError)
at System.Web.ImpersonationData.GetImpersonationToken(Boolean
forGlobalCode, Boolean throwOnError)
at System.Web.ImpersonationData.Start(Boolean forGlobalCode, Boolean
throwOnError, Boolean fromAnotherThread)
at System.Web.HttpApplication.OnThreadEnter()
at System.Web.HttpApplication.ResumeSteps(Exception error)"

Thanks.