.Net程序集加载问题期间出现BadImageFormatException

当我尝试访问页面时(默认.aspx)在iis7.0的一个网站(在windowsserver2008上使用vsts2010+.net4.0开发)中,我遇到了以下错误消息。有什么问题吗?什么意思

顺便说一句:我运行的是64位的WindowsServer2008(不是R2),还没有激活WindowsServer2008,这可能是根本原因吗?

[BadImageFormatException: Could not load file or assembly 'test.foo' or one of its dependencies. Try to load bad formatted program. ]
   System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +0
   System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection, Boolean suppressSecurityChecks) +567
   System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +192
   System.Reflection.Assembly.Load(String assemblyString) +35
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +118

[ConfigurationErrorsException: Could not load file or assembly 'test.foo' or one of its dependencies.  Try to load bad formatted program. ]
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +11392147
   System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +484
   System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +127
   System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +334
   System.Web.Compilation.BuildManager.CallPreStartInitMethods() +280
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +1087

[HttpException (0x80004005): Could not load file or assembly 'test.foo' or one of its dependencies.  Try to load bad formatted program. ]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11524352
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4782309