Using SHGetFileInfo causes Assertion

My program mirrors Windows Explorer with two views one a CTreeView and
the other CListView derieved classes. My program makes use of
SHGetFileInfo twice once in the derieved CTreeView and the other in
the CListView derieved class. I am not sure how to make use of this
function only for both views. If anyone has any ideas please share.

Running the code in Debug mode causes an Assertion window to appear.
But if I choose Continue (with the code execution) from the Debug
window the main application window appears normally without any
further errors and all icons are display correctly in both views. Also
if run the code in Release mode the code works without any errors with
both views displaying correct icons beside each entry/item.

When the code causes an Asssertion it takes place at the below line or
at least that is where the code stops in the Debugger (using VS 2005
Standard). It says my application has triggered a Breakpoint and an
option of to Continue or Break is given. If Break is chosen then this
line below is where the code stops. If you choose Continue the main
window opens and everything is displayed normally.

// within the CListView class
if ( !m_imgList.Attach( hImgList ) )

Any ideas as to why the assertion takes place ? Should I worry about
it since it appears only in Debug mode and ignoring the Assertion and
continuing with the execution the windows still displays correctly ?
Is there a shortcoming with my code ? Any suggestions would be greatly
appreciated.

BOOL CMyListView::GetSysImgList()
{
SHFILEINFO shFinfo;
HIMAGELIST hImgList = NULL;

CListCtrl& m_listCtrl = GetListCtrl( );

if ( m_listCtrl.GetImageList( TVSIL_NORMAL ) )
     m_imgList.Detach();

hImgList = (HIMAGELIST)SHGetFileInfo( _T("C:\\"), 0, &shFinfo, sizeof
( SHFILEINFO ), SHGFI_SYSICONINDEX | SHGFI_SMALLICON);

if ( !hImgList )
{
      m_strError = "Cannot retrieve the Handle of SystemImageList!";
      return FALSE;
}

if ( !m_imgList.Attach( hImgList ) )
{
   m_strError = "Cannot Attach SystemImageList-Handle";
   return FALSE;
}

m_listCtrl.SetImageList( &m_imgList, LVSIL_SMALL );
return TRUE; // OK
}