ASP.NET websites fail with: "The file or directory is corrupted and unreadable. (Exception from HRESULT: 0x80070570) "

Any web site that I run with ASP.NET code fails with an error that includes the above.  Some times an explicit assemby is mentioned, but I have sites that just fail : Exception Details - System.BadImageFormatException: The file or directory is corrupted and unreadable.

here is the full error response from one site:

Server Error in '/' Application.
--------------------------------------------------------------------------------

Could not load file or assembly 'System.Web.Extensions' or one of its dependencies. The file or directory is corrupted and unreadable. (Exception from HRESULT: 0x80070570)
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.

Exception Details: System.BadImageFormatException: Could not load file or assembly 'System.Web.Extensions' or one of its dependencies. The file or directory is corrupted and unreadable. (Exception from HRESULT: 0x80070570)

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.  

Assembly Load Trace: The following information can be helpful to determine why the assembly 'System.Web.Extensions' could not be loaded.


WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

 

Stack Trace:


[BadImageFormatException: Could not load file or assembly 'System.Web.Extensions' or one of its dependencies. The file or directory is corrupted and unreadable. (Exception from HRESULT: 0x80070570)]

[BadImageFormatException: Could not load file or assembly 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The file or directory is corrupted and unreadable. (Exception from HRESULT: 0x80070570)]
   System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0
   System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +43
   System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +127
   System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +142
   System.Reflection.Assembly.Load(String assemblyString) +28
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +46

[ConfigurationErrorsException: Could not load file or assembly 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The file or directory is corrupted and unreadable. (Exception from HRESULT: 0x80070570)]
   System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +613
   System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +203
   System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +105
   System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +178
   System.Web.Compilation.BuildProvidersCompiler..ctor(VirtualPath configPath, Boolean supportLocalization, String outputAssemblyName) +54
   System.Web.Compilation.CodeDirectoryCompiler.GetCodeDirectoryAssembly(VirtualPath virtualDir, CodeDirectoryType dirType, String assemblyName, StringSet excludedSubdirectories, Boolean isDirectoryAllowed) +600
   System.Web.Compilation.BuildManager.CompileCodeDirectory(VirtualPath virtualDir, CodeDirectoryType dirType, String assemblyName, StringSet excludedSubdirectories) +125
   System.Web.Compilation.BuildManager.CompileResourcesDirectory() +31
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +304

[HttpException (0x80004005): Could not load file or assembly 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The file or directory is corrupted and unreadable. (Exception from HRESULT: 0x80070570)]
   System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +58
   System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +512
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) +729

[HttpException (0x80004005): Could not load file or assembly 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The file or directory is corrupted and unreadable. (Exception from HRESULT: 0x80070570)]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +8897659
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +85
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +333

 
Note the 80004005 HTTP exceptions in the stack trace.  I am running this as an administrator on the localhost with full access to files.

I think this is something to do with permissions on the .net 2 framework temp folder, but this has been cleared and everyone now has modify rights on the folder