AccessViolation calling COleDataSource::DoDragDrop from C++/CLI

Here's a quick background on what I'm trying to acomplish:

I'm trying to drag drop virtual files by deriving System::Windows::Forms::ListView in my own class and using unmanaged code to delay render.

Here's my OnItemDrag override:
1 virtual void OnItemDrag(ItemDragEventArgs ^e) override  
2 {  
3     UINT uFileCount = this->SelectedItems->Count;  
4     UINT uBuffSize = sizeof(FILEGROUPDESCRIPTOR) +    
5         (uFileCount-1) * sizeof(FILEDESCRIPTOR);  
6     HGLOBAL hFileDescriptor = GlobalAlloc (    
7         GHND | GMEM_SHARE, uBuffSize );  
8     if(hFileDescriptor)  
9     {  
10         FILEGROUPDESCRIPTOR* pGroupDescriptor =    
11             (FILEGROUPDESCRIPTOR*) GlobalLock ( hFileDescriptor );  
12         if(pGroupDescriptor)  
13         {  
14             FILEDESCRIPTOR* pFileDescriptorArray =    
15                 (FILEDESCRIPTOR*)((LPBYTE)pGroupDescriptor + sizeof(UINT));  
16             pGroupDescriptor->cItems = uFileCount;  
17             int index = 0;  
18             m_pDataSrc->m_Files->RemoveAll();  
19             for (int i = 0; i < uFileCount; ++i)  
20             {  
21                 ZeroMemory(&pFileDescriptorArray[index],    
22                     sizeof(FILEDESCRIPTOR));                      
23  
24                 pin_ptr<const wchar_t> wch = PtrToStringChars(this->SelectedItems[i]->Text);  
25  
26                 CString fileName(wch);  
27  
28                 lstrcpy ( pFileDescriptorArray[index].cFileName, fileName );  
29  
30                 m_pDataSrc->m_Files->Add(pFileDescriptorArray[index].cFileName);  
31                 pFileDescriptorArray[index].dwFlags = FD_FILESIZE|FD_ATTRIBUTES;  
32                 pFileDescriptorArray[index].nFileSizeLow = 512;  
33                 pFileDescriptorArray[index].nFileSizeHigh = 0;  
34                 pFileDescriptorArray[index].dwFileAttributes = FILE_ATTRIBUTE_NORMAL;  
35                 index++;  
36             }  
37         }  
38         else  
39         {  
40             GlobalFree ( hFileDescriptor );  
41         }  
42     }  
43     GlobalUnlock ( hFileDescriptor );      
44  
45     FORMATETC etcDescriptor = {    
46         RegisterClipboardFormat(CFSTR_FILEDESCRIPTOR),    
47         NULL, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };  
48         m_pDataSrc->CacheGlobalData ( RegisterClipboardFormat(  
49             CFSTR_FILEDESCRIPTOR), hFileDescriptor, &etcDescriptor );  
50  
51     FORMATETC etcContents = {    
52         RegisterClipboardFormat(CFSTR_FILECONTENTS),    
53         NULL, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };  
54  
55     m_pDataSrc->DelayRenderFileData(  
56         RegisterClipboardFormat(CFSTR_FILECONTENTS),    
57         &etcContents);  
58  
59     DROPEFFECT dwEffect = m_pDataSrc->DoDragDrop (    
60         DROPEFFECT_COPY | DROPEFFECT_MOVE );              
61  
62     if(dwEffect == DROPEFFECT_NONE )  
63     {  
64         GlobalFree( hFileDescriptor );  
65     }    
66 }  

I'm getting an AccessViolationException on line 59 - the call to DoDragDrop.

Here's the definition of m_pDataSrc:
protected:  
    CMyOleDataSource * m_pDataSrc;  

It gets instanciated using new in the class constructor.

Here is the implementation of CMyOleDataSource:

[.h file]
1  
2 #pragma once  
3  
4 #include <afxwin.h>         // MFC core and standard components  
5 #include <afxext.h>         // MFC extensions  
6  
7 #include <afxdisp.h>        // MFC Automation classes  
8  
9 #ifndef _AFX_NO_OLE_SUPPORT  
10 #include <afxdtctl.h>       // MFC support for Internet Explorer 4 Common Controls  
11 #endif  
12 #ifndef _AFX_NO_AFXCMN_SUPPORT  
13 #include <afxcmn.h>         // MFC support for Windows Common Controls  
14 #endif // _AFX_NO_AFXCMN_SUPPORT  
15 #include <afxole.h>  
16  
17 // CMyOleDataSource command target  
18  
19 class CMyOleDataSource : public COleDataSource  
20 {  
21     DECLARE_DYNAMIC(CMyOleDataSource)  
22  
23 public:  
24     CMyOleDataSource();  
25     virtual ~CMyOleDataSource() { delete m_Files; }  
26     virtual BOOL OnRenderFileData(LPFORMATETC lpFormatEtc,CFile* pFile);  
27     CStringArray *m_Files;  
28  
29 protected:  
30     DECLARE_MESSAGE_MAP()  
31 };  

[.cpp file]
1 // MyOleDataSource.cpp : implementation file  
2 //  
3  
4 #include "stdafx.h"
5 #include "MyOleDataSource.h"  
6  
7  
8 // CMyOleDataSource  
9  
10 IMPLEMENT_DYNAMIC(CMyOleDataSource, COleDataSource)  
11  
12  
13 CMyOleDataSource::CMyOleDataSource()  
14 {  
15     m_Files = new CStringArray();  
16 }  
17  
18 BEGIN_MESSAGE_MAP(CMyOleDataSource, COleDataSource)  
19 END_MESSAGE_MAP()  
20  
21  
22  
23 // CMyOleDataSource message handlers  
24  
25 BOOL CMyOleDataSource::OnRenderFileData(  
26     LPFORMATETC lpFormatEtc,CFile* pFile)  
27 {  
28     if(lpFormatEtc->cfFormat ==    
29         RegisterClipboardFormat(CFSTR_FILECONTENTS))  
30     {      
31         HGLOBAL hGlob = NULL;  
32         const int buffSize = 512;  
33         hGlob = GlobalAlloc(GMEM_FIXED, buffSize);  
34         if(hGlob)  
35         {  
36             LPBYTE pBytes = (LPBYTE)GlobalLock(hGlob);            
37             if(pBytes)  
38             {  
39                 memset(pBytes, (int) m_Files->GetAt(  
40                     lpFormatEtc->lindex)[0], buffSize);  
41                 pFile->Write(pBytes,buffSize);                
42             }  
43             GlobalUnlock(hGlob);  
44         }  
45         GlobalFree(hGlob);  
46         return TRUE;  
47     }  
48     return COleDataSource::OnRenderFileData(  
49         lpFormatEtc, pFile);  
50 }  

Any ideas why I would be getting an AccessViolation?

Thanks,
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