Could not load file or assembly stdole

Just installed VS2015 side by side with VS2010...

Application in issue was built using VS2010 (set to use .Net 4.0) (not migrated to VS2015) worked fine on my machine, put it on server and fell over in a heap... stdole was the issue...

In the error Windows Logs > Applications there was an exception:

Exception information: 
Exception type: ConfigurationErrorsException 
Exception message: Could not load file or assembly 'stdole, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. Strong name signature could not be verified.  The assembly may have been tampered with, or it was delay signed but not fully signed with the correct private key. (Exception from HRESULT: 0x80131045)
   at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)
   at System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory()
   at System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai)
   at System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig)
   at System.Web.Compilation.BuildManager.GetPreStartInitMethodsFromReferencedAssemblies()
   at System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded)
   at System.Web.Compilation.BuildManager.ExecutePreAppStart()
   at System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException)

Could not load file or assembly 'stdole, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. Strong name signature could not be verified.  The assembly may have been tampered with, or it was delay signed but not fully signed with the correct private key. (Exception from HRESULT: 0x80131045)
   at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at     System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean forIntrospection)
   at System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.Load(String assemblyString)
   at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)

Could not load file or assembly 'stdole' or one of its dependencies. Strong name signature could not be verified.  The assembly may have been tampered with, or it was delay signed but not fully signed with the correct private key. (Exception from HRESULT: 0x80131045)

Stack trace:    at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)
   at System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory()
   at System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai)
   at System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig)
   at System.Web.Compilation.BuildManager.GetPreStartInitMethodsFromReferencedAssemblies()
   at System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded)
   at System.Web.Compilation.BuildManager.ExecutePreAppStart()
   at System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException)

Looked at reference to stdole and it was to the GAC and to a Version: 2.0.0.0

The bitness of nothing has changed.

Where on earth has this error come from?

Just in case anyone else encounters the issue the same way I did...

This is how I resolved the issue:

Deleted the existing reference to stdole, then added a reference > extensions > there were four entries for stdole! one with the office icon, one with the VS icon, one with a cog (setup icon) and another with no icon (all four were exactly the same version numbers etc)...

Added a reference to the one with VS icon and deployed to server... all going well (touch wood)