Unhandled Exceptions different in 64bit? / vs2008

[hobnob]

I have a program that works fine in 32bit mode on vs6.

but in 2008 64bit it sometimes gets an unhandled exception crash in the following code (PostMessage line):-

Is something different in 64bit vs2008? error is: Access violation reading location


if(wnd && ::IsWindow(wnd->m_hWnd))
{
try
{
wnd->PostMessage(WM_COMMAND,MAKELONG(0x01,BN_CLICKED),(LPARAM)(wnd->GetDlgItem(0x01))->m_hWnd); // post ok to message
}
catch(...)
{

// do nothing
}
}