w3wp.exe crashes with C0000005 at HttpResponse.Flush. Call Stack as below.
00 (Inline Function) --------`-------- iiscore!W3_CONTEXT_BASE::QueryW3Context
01 00000061`5688e0b0 00007ffc`3db55718 iiscore!NOTIFICATION_SEND_RESPONSE::GetHeadersBeingSent(void)+0xa
02 00000061`5688e0e0 00007ffc`3db542d8 authmd5!AUTH_PROVIDER::DoWork(unsigned long dwRequestNotification = 0x20000000, class IHttpContext * pRequestContext = 0x0000005d`09d7f410, class IHttpEventProvider * pRequestOutput = 0x00000061`55fb0a68)+0x64
03 (Inline Function) --------`-------- authmd5!RequestDoWork+0x10
04 00000061`5688e220 00007ffc`3e419c1b authmd5!CIISHttpModule::OnSendResponse(class IHttpContext * pHttpContext = <Value unavailable error>, class ISendResponseProvider * pProvider = <Value unavailable error>)+0x14
05 00000061`5688e260 00007ffc`3e412908 iiscore!NOTIFICATION_CONTEXT::RequestDoWork(class CHttpModule * pCHttpModule = 0x0000005d`09b095e8, class W3_CONTEXT_BASE * pRequestContext = 0x0000005d`09d7f410, class IHttpCompletionInfo2 * pCompletion = 0x00000000`00000000, class IHttpEventProvider * pRequestOutput = 0x00000061`55fb0a68)+0xb1
06 00000061`5688e2a0 00007ffc`3e4119a6 iiscore!NOTIFICATION_CONTEXT::CallModulesInternal(int fCompletion = 0n0, unsigned long cbCompletion = 0, HRESULT hrCompletionStatus = 0x00000000, unsigned long dwCompletedOperation = 0, class W3_CONTEXT_BASE * pRequestContext = 0x0000005d`09d7f410, class IHttpEventProvider * pRequestOutput = 0x00000061`55fb0a68)+0x198
07 00000061`5688e3b0 00007ffc`3e41b517 iiscore!NOTIFICATION_CONTEXT::CallModules(int fCompletion = 0n955466581, unsigned long cbCompletion = 1, HRESULT hrCompletionStatus = 0x00000001, unsigned long dwCompletedOperation = 0, class W3_CONTEXT_BASE * pRequestContext = 0x0000005d`09d7f410, class IHttpEventProvider * pRequestOutput = 0x00000061`55fb0a68)+0x36
08 00000061`5688e410 00007ffc`3e41b2dc iiscore!NOTIFICATION_SEND_RESPONSE::DoWork(unsigned long cbCompletion = 0, HRESULT hrCompletionStatus = <Value unavailable error>, unsigned long dwCompletedOperation = <Value unavailable error>, int fCompletion = 0n0)+0x87
09 00000061`5688e490 00007ffc`3e41bdfa iiscore!W3_CONTEXT_BASE::StartNotificationLoop(class NOTIFICATION_CONTEXT * pNotificationContext = 0x00000061`55fb09e0, int fForceSynchronous = 0n1)+0x94
0a 00000061`5688e4d0 00007ffc`3e41f5df iiscore!W3_RESPONSE::Flush(int fAsync = 0n0, int fMoreData = <Value unavailable error>, class W3_CONTEXT_BASE * pW3BaseContext = 0x0000005d`09d7f410, unsigned long * pcbSent = 0x00000061`5688e628, int * pfCompletionExpected = 0x00000061`5688e610)+0x30a
0b 00000061`5688e560 00007ffc`3e10e141 iiscore!RESPONSE_CONTEXT::Flush(int fAsync = <Value unavailable error>, int fMoreData = <Value unavailable error>, unsigned long * pcbSent = <Value unavailable error>, int * pfCompletionExpected = 0x00000061`5688e610)+0x23
0c 00000061`5688e5a0 00007ffc`1ab8521f webengine4!W3_MGD_HANDLER::ExplicitFlush(int fAsync = 0n955538661, int * pfCompletedSynchronously = 0x00000000`00000000)+0x9a
0d 00000061`5688e610 00007ffc`1ac8b130 System_Web_ni!DomainNeutralILStubClass.IL_STUB_PInvoke(<HRESULT 0x80004001>)+0x8f
0e 00000061`5688e6f0 00007ffc`1abb9db0 System_Web_ni!System.Web.Hosting.IIS7WorkerRequest.ExplicitFlush(<HRESULT 0x80004001>)+0x20
0f 00000061`5688e730 00007ffc`1abf4fd0 System_Web_ni!System.Web.HttpResponse.Flush(<HRESULT 0x80004001>)+0xc0
10 00000061`5688e790 00007ffc`38569086 System_Web_ni!System.Web.HttpWriter.WriteFromStream(<HRESULT 0x80004001>)+0xa0
11 00000061`5688e7f0 00007ffc`38bd1d28 mscorlib_ni!System.IO.Stream.<BeginWriteInternal>b__11(<HRESULT 0x80004001>)+0x46
A lot C0000005 AccessViolationException is caused by heap corruption but this one is not.
The problem is caused by that some other threads manipulated the response during the response flush and caused object no longer exists, or holding the objects so Response.Flush cannot access it.
The best to identify what exactly caused the problem is to capture a crash dump and examine each thread's call stack.
