>Did you install the .Net 4.5 runtimes?

Right now, my framework and my client projects are set to .NET Framework 4.0. Even with that setting, do I really need the .Net 4.5 runtimes?

Here is more information. I set the registry HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Fusion EnableLog to 1. This gives me more information:

=== Pre-bind state information ===
LOG: User = something\something
LOG: DisplayName = Framework
(Partial)
WRN: Partial binding information was supplied for an assembly:
WRN: Assembly Name: Framework | Domain ID: 2
WRN: A partial bind occurs when only part of the assembly display name is provided.
WRN: This might result in the binder loading an incorrect assembly.
WRN: It is recommended to provide a fully specified textual identity for the assembly,
WRN: that consists of the simple name, version, culture, and public key token.
WRN: See whitepaper http://go.microsoft.com/fwlink/?LinkId=109270 for more information and common solutions to this issue.
LOG: Appbase = file:///D:/iis/Universal Thread/
LOG: Initial PrivatePath = D:\iis\Universal Thread\bin
Calling assembly : (Unknown).
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: D:\iis\Universal Thread\web.config
LOG: Using host configuration file: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/universalthread/c9af4643/2449e21f/Framework.DLL.
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/universalthread/c9af4643/2449e21f/Framework/Framework.DLL.
LOG: Attempting download of new URL file:///D:/iis/Universal Thread/bin/Framework.DLL.
ERR: Failed to complete setup of assembly (hr = 0x8007000b). Probing terminated.

And, then, the StackTrace as before:

[BadImageFormatException: Could not load file or assembly 'Framework' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +0
System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +210
System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean forIntrospection) +242
System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +17
System.Reflection.Assembly.Load(String assemblyString) +35
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +122

[ConfigurationErrorsException: Could not load file or assembly 'Framework' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +12761078
System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +503
System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +142
System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +334
System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath) +203
System.Web.Compilation.BuildManager.ExecutePreAppStart() +152
System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +1151

[HttpException (0x80004005): Could not load file or assembly 'Framework' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +12881540
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +159
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +12722601