Exception seen WCF/IIS7.0 Implementation NHibernate.HibernateException: Creating a proxy instance failed

Has anyone seen the following exception and knows what the cause is. Recently deployed code live and started seeing exceptions which forced roll back. On Windows Server 2008 and IIS7.0. The full stack trace seen below.

NHibernate.HibernateException: Creating a proxy instance failed ---> System.Runtime.InteropServices.COMException (0x800703FA): Illegal operation attempted on a registry key that has been marked for deletion. (Exception from HRESULT: 0x800703FA)

at System.Reflection.Assembly._nDefineDynamicModule(Assembly containingAssembly, Boolean emitSymbolInfo, String filename, StackCrawlMark& stackMark)

at System.Reflection.Emit.AssemblyBuilder.DefineDynamicModuleInternalNoLock(String name, Boolean emitSymbolInfo, StackCrawlMark& stackMark)

at System.Reflection.Emit.AssemblyBuilder.DefineDynamicModuleInternal(String name, Boolean emitSymbolInfo, StackCrawlMark& stackMark)

at System.Reflection.Emit.AssemblyBuilder.DefineDynamicModule(String name, Boolean emitSymbolInfo)

at Castle.DynamicProxy.ModuleScope.CreateModule(Boolean signStrongName)

at Castle.DynamicProxy.ModuleScope.ObtainDynamicModuleWithWeakName()

at Castle.DynamicProxy.Generators.Emitters.ClassEmitter.CreateTypeBuilder(ModuleScope modulescope, String name, Type baseType, Type[] interfaces, TypeAttributes flags, Boolean forceUnsigned)

at Castle.DynamicProxy.Generators.Emitters.ClassEmitter..ctor(ModuleScope modulescope, String name, Type baseType, Type[] interfaces, TypeAttributes flags, Boolean forceUnsigned)

at Castle.DynamicProxy.Generators.Emitters.ClassEmitter..ctor(ModuleScope modulescope, String name, Type baseType, Type[] interfaces)

at Castle.DynamicProxy.Generators.BaseProxyGenerator.BuildClassEmitter(String typeName, Type parentType, Type[] interfaces)

at Castle.DynamicProxy.Generators.ClassProxyGenerator.GenerateCode(Type[] interfaces, ProxyGenerationOptions options)

at Castle.DynamicProxy.ProxyGenerator.CreateClassProxy(Type classToProxy, Type[] additionalInterfacesToProxy, ProxyGenerationOptions options, Object[] constructorArguments, IInterceptor[] interceptors)

at Castle.DynamicProxy.ProxyGenerator.CreateClassProxy(Type classToProxy, Type[] additionalInterfacesToProxy, IInterceptor[] interceptors)

at NHibernate.ByteCode.Castle.ProxyFactory.GetProxy(Object id, ISessionImplementor session)

This might be a potential fix for you: http://blogs.msdn.com/b/distributedservices/archive/2009/11/06/a-com-server-application-may-stop-working-on-windows-server-2008.aspx