asp.net-mvc-3 – ASP.NET MVC 3 RTM项目中的这个错误是什么？

但是当我再次运行项目时,得到这个例外：

[A]System.Web.WebPages.Razor.Configuration.HostSection
cannot be cast to
[B]System.Web.WebPages.Razor.Configuration.HostSection.
Type A originates from
‘System.Web.WebPages.Razor,
Version=1.0.0.0,Culture=neutral,
PublicKeyToken=31bf3856ad364e35’ in
the context ‘Default’ at location
‘C:WindowsMicrosoft.NetassemblyGAC_MSILSystem.Web.WebPages.Razorv4.0_1.0.0.0__31bf3856ad364e35System.Web.WebPages.Razor.dll’.
Type B originates from
‘System.Web.WebPages.Razor,
PublicKeyToken=null’ in the context
‘Default’ at location
‘C:WindowsMicrosoft.NETFrameworkv4.0.30319Temporary
ASP.NET
Filesroot2505c7ee369315c5assemblydl3f7bae428d03eeed8_85bbcb01System.Web.WebPages.Razor.DLL’.

Description: An unhandled exception
occurred during the execution of the
current web request. Please review the
stack trace for more information about
the error and where it originated in
the code.

源错误：

Line 106:        internal static RazorWebSectionGroup GetRazorSection(string virtualPath) {
Line 107:            // Get the individual sections (we can only use GetSection in medium trust) and then reconstruct the section group
Line 108:            return new RazorWebSectionGroup() {
Line 109:                Host = (HostSection)WebConfigurationManager.GetSection(HostSection.SectionName,virtualPath),Line 110:                Pages = (RazorPagesSection)WebConfigurationManager.GetSection(RazorPagesSection.SectionName,virtualPath)

Source File:
E:GreenTourwebpagessrcSystem.Web.WebPages.RazorWebRazorHostFactory.cs
Line: 108