Why "Optimize Code" is needed to be turned on for my program to run without crashing?

I was given this WPF application, when I tried to run the program in Debug mode it would crash before getting to Windows1.xml. I later tried running in Release Mode and it would run successfully. I narrowed it down to that, I needed to turn on "Optimize Code" for it to work.

Note: Breakpoints, stepping into from debug, and stopping on throw exceptions don't work.

Edit: The exception was WPF (very popular & not helpful) generic exception:

{"Cannot create instance of 'Main' defined in assembly 'VCell2, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. Exception has been thrown by the target of an invocation. Error in markup file 'Window1.xaml' Line 1 Position 9."} Source="PresentationFramework" LineNumber=1 LinePosition=9

Edit: The inner - inner exception: {"The specified module could not be found. (Exception from HRESULT: 0x8007007E)":null}

Here was the stack trace I was getting:

   at System.Windows.Markup.XamlParseException.ThrowException(String message, Exception innerException, Int32 lineNumber, Int32 linePosition, Uri baseUri, XamlObjectIds currentXamlObjectIds, XamlObjectIds contextXamlObjectIds, Type objectType)
   at System.Windows.Markup.XamlParseException.ThrowException(ParserContext parserContext, Int32 lineNumber, Int32 linePosition, String message, Exception innerException)
   at System.Windows.Markup.BamlRecordReader.ThrowExceptionWithLine(String message, Exception innerException)
   at System.Windows.Markup.BamlRecordReader.CreateInstanceFromType(Type type, Int16 typeId, Boolean throwOnFail)
   at System.Windows.Markup.BamlRecordReader.GetElementAndFlags(BamlElementStartRecord bamlElementStartRecord, Object& element, ReaderFlags& flags, Type& delayCreatedType, Int16& delayCreatedTypeId)
   at System.Windows.Markup.BamlRecordReader.BaseReadElementStartRecord(BamlElementStartRecord bamlElementRecord)
   at System.Windows.Markup.BamlRecordReader.ReadElementStartRecord(BamlElementStartRecord bamlElementRecord)
   at System.Windows.Markup.BamlRecordReader.ReadRecord(BamlRecord bamlRecord)
   at System.Windows.Markup.BamlRecordReader.Read(Boolean singleRecord)
   at System.Windows.Markup.TreeBuilderBamlTranslator.ParseFragment()
   at System.Windows.Markup.TreeBuilder.Parse()
   at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream)
   at System.Windows.Application.LoadBamlStreamWithSyncInfo(Stream stream, ParserContext pc)
   at System.Windows.Application.LoadComponent(Uri resourceLocator, Boolean bSkipJournaledProperties)
   at System.Windows.Application.DoStartup()
   at System.Windows.Application.<.ctor>b__0(Object unused)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
   at System.Windows.Threading.DispatcherOperation.InvokeImpl()
   at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
   at System.Threading.ExecutionContext.runTryCode(Object userData)
   at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Windows.Threading.DispatcherOperation.Invoke()
   at System.Windows.Threading.Dispatcher.ProcessQueue()
   at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter)
   at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.Run()
   at System.Windows.Application.RunDispatcher(Object ignore)
   at System.Windows.Application.RunInternal(Window window)
   at System.Windows.Application.Run(Window window)
   at System.Windows.Application.Run()
   at VCell2.App.Main() in C:\Users\wandrus\Documents\Visual Studio 2008\Projects\VCell2\VCell2\obj\Debug\App.g.cs:line 0

Edit I've tried running it windbg (don't know if I'm doing this correctly)

ModLoad: 77310000 773b0000   C:\Windows\system32\ADVAPI32.dll
ModLoad: 76a30000 76adc000   C:\Windows\system32\msvcrt.dll
ModLoad: 76c60000 76c79000   C:\Wi开发者_开发技巧ndows\SYSTEM32\sechost.dll
ModLoad: 76ae0000 76b82000   C:\Windows\system32\RPCRT4.dll
ModLoad: 770c0000 77117000   C:\Windows\system32\SHLWAPI.dll
ModLoad: 76940000 7698e000   C:\Windows\system32\GDI32.dll
ModLoad: 76c80000 76d49000   C:\Windows\system32\USER32.dll
ModLoad: 778e0000 778ea000   C:\Windows\system32\LPK.dll
ModLoad: 77120000 771bd000   C:\Windows\system32\USP10.dll
ModLoad: 76ea0000 76ebf000   C:\Windows\system32\IMM32.DLL
ModLoad: 76b90000 76c5c000   C:\Windows\system32\MSCTF.dll
ModLoad: 6c1b0000 6c1b5000   C:\Windows\system32\avgrsstx.dll
ModLoad: 57310000 578a1000   C:\Windows\Microsoft.NET\Framework\v2.0.50727\mscorwks.dll
ModLoad: 756a0000 7573b000   C:\Windows\WinSxS\x86_microsoft.vc80.crt_1fc8b3b9a1e18e3b_8.0.50727.4918_none_d089094c442eb5ff\MSVCR80.dll
ModLoad: 75c40000 76886000   C:\Windows\system32\shell32.dll
ModLoad: 773c0000 7751b000   C:\Windows\system32\ole32.dll
ModLoad: 75810000 7581b000   C:\Windows\system32\profapi.dll
ModLoad: 53de0000 548d8000   C:\Windows\assembly\NativeImages_v2.0.50727_32\mscorlib\70603943245265de9397091048337dda\mscorlib.ni.dll
ModLoad: 757a0000 757ac000   C:\Windows\system32\CRYPTBASE.dll
ModLoad: 744f0000 74530000   C:\Windows\system32\uxtheme.dll
ModLoad: 52ea0000 53639000   C:\Windows\assembly\NativeImages_v2.0.50727_32\System\ade9214f5bce88462742bce1278864c0\System.ni.dll
ModLoad: 57ae0000 57e0c000   C:\Windows\assembly\NativeImages_v2.0.50727_32\WindowsBase\c7663f3a74fb6aa480c60108634d285a\WindowsBase.ni.dll
ModLoad: 03eb0000 04a5b000   C:\Windows\assembly\NativeImages_v2.0.50727_32\PresentationCore\c79b7f336e6099b8c94081f975e9411e\PresentationCore.ni.dll
ModLoad: 55240000 55fec000   C:\Windows\assembly\NativeImages_v2.0.50727_32\PresentationFramewo#\7d80b7d912fbf0f7532f1b9adc235646\PresentationFramework.ni.dll
ModLoad: 00e50000 01255000   PresentationCore.dll
ModLoad: 00e50000 01255000   PresentationCore.dll
ModLoad: 539d0000 53b7c000   C:\Windows\Microsoft.NET\Framework\v3.0\WPF\wpfgfx_v0300.dll
ModLoad: 76990000 76a1f000   C:\Windows\system32\OLEAUT32.dll
ModLoad: 51520000 51754000   C:\Windows\assembly\NativeImages_v2.0.50727_32\System.Core\e78709bedd31f237055667ad99b9451f\System.Core.ni.dll
ModLoad: 6cbc0000 6cc1b000   C:\Windows\Microsoft.NET\Framework\v2.0.50727\mscorjit.dll
ModLoad: 637d0000 638c1000   C:\Windows\assembly\NativeImages_v2.0.50727_32\System.Configuration\9c2727d244dcc72fbefcf1ae22660f35\System.Configuration.ni.dll
ModLoad: 57f20000 58456000   C:\Windows\assembly\NativeImages_v2.0.50727_32\System.Xml\93d38ea87365928456313035f8091126\System.Xml.ni.dll
ModLoad: 74130000 74143000   C:\Windows\system32\dwmapi.dll
ModLoad: 60340000 60348000   C:\Windows\Microsoft.NET\Framework\v2.0.50727\culture.dll
(1e2c.738): C++ EH exception - code e06d7363 (first chance)
(1e2c.738): C++ EH exception - code e06d7363 (first chance)
(1e2c.738): C++ EH exception - code e06d7363 (first chance)
(1e2c.738): C++ EH exception - code e06d7363 (first chance)
(1e2c.738): C++ EH exception - code e06d7363 (first chance)
(1e2c.738): C++ EH exception - code e06d7363 (first chance)
(1e2c.738): C++ EH exception - code e06d7363 (first chance)
(1e2c.738): CLR exception - code e0434f4d (first chance)
(1e2c.738): C++ EH exception - code e06d7363 (first chance)
(1e2c.738): CLR exception - code e0434f4d (first chance)
(1e2c.738): CLR exception - code e0434f4d (first chance)
(1e2c.738): CLR exception - code e0434f4d (first chance)
(1e2c.738): CLR exception - code e0434f4d (!!! second chance !!!)
eax=0025e034 ebx=e0434f4d ecx=00000001 edx=00000000 esi=0025e0bc edi=002d66d8
eip=75acb4f4 esp=0025e034 ebp=0025e084 iopl=0         nv up ei pl nz ac po nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000212
*** ERROR: Symbol file could not be found.  Defaulted to export symbols for C:\Windows\system32\KERNELBASE.dll - 
KERNELBASE!RaiseException+0x54:
75acb4f4 c9              leave

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You need to provide more information. What is the exception? It could be that a type is being referenced at runtime that can't be resolved. If the code isn't being used, the optimizer might just omit it from JIT whereas in debug mode it could be triggering a type load exception. Who knows though. Without more info it'd be impossible to tell.

edit in response to the update in your question, it seems like there's a type called Main that is throwing an exception in its instance constructor or static constructor. It could also be a field initializer that's triggering this. If you can catch the exception, check its InnerException which TargetInvocationExceptions usually contain. This will give you more info.

edit you've indicated that the inner exception is an assembly loading problem which is what i figured initially. so you're missing a reference somewhere. in particular, you are probably referencing a DLL that in turn references another DLL that cannot be located. You'll need to figure out which assembly can't be resolved. You can use the fuslogvw.exe tool to view assembly binding errors.