Having installed VS2005 pro yesterday (MSDN download version) I am
gradually moving my VS2003 stuff over. I am having a problem with
IContextMenu3.HandleMenuMsg (called when the Explorer Context Menu is
shown) although it worked fine in VS2003. I get an error:

System.AccessViolationException was unhandled
 Message="Attempted to read or write protected memory. This is often
an indication that other memory is corrupt."
 Source="JGLibDLL"
 StackTrace:
      at JGLibDLL.IContextMenu2.HandleMenuMsg(UInt32 uMsg, UInt32
wParam, UInt32 lParam)
... rest of trace omitted.

It is called from WndProc:

protected override void WndProc(ref Message message)
{
//    NB call base first or some user drawn menu items will not display
properly!
    base.WndProc(ref message);
    const int WM_DRAWITEM = 0x002B;
    const int WM_MEASUREITEM= 0x002C;
    const int WM_INITMENUPOPUP= 0x0117;
    const int WM_MENUCHAR = 0x0120;

    IntPtr lpResult = IntPtr.Zero;
           
    switch (message.Msg)
    {
        case WM_DRAWITEM:
        case WM_MEASUREITEM:
        case WM_INITMENUPOPUP:
        if(m_IContextMenu3 != null)
            m_IContextMenu3.HandleMenuMsg((uint)message.Msg,
(uint)message.WParam, (uint)message.LParam);
        break;

        case WM_MENUCHAR:
        if(m_IContextMenu3 != null)
            m_IContextMenu3.HandleMenuMsg2((uint)message.Msg,
(uint)message.WParam, (uint)message.LParam, lpResult);
        break;
        default:
        break;
    }
}

The Interfaces are defined:

[ComImport]
[Guid("000214e4-0000-0000-c000-000000000046")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IContextMenu : IUnknown
{
    [PreserveSig()]
    int QueryContextMenu(uint hMenu, uint indexMenu, int idCmdFirst, int
idCmdLast, uint uFlags);

    [PreserveSig]
    int InvokeCommand(ref CMINVOKECOMMANDINFO lpici) ;

    [PreserveSig()]
    void GetCommandString(int idcmd, uint uflags, int reserved, IntPtr
commandstring, int cch);
}

[ComImport]
[Guid("000214F4-0000-0000-c000-000000000046")]
public interface IContextMenu2 : IContextMenu
{
    [PreserveSig]
    int HandleMenuMsg(uint uMsg, uint wParam, uint lParam);
}

[ComImport]
[Guid("bcfce0a0-ec17-11d0-8d10-00a0c90f2719")]
public interface IContextMenu3 : IContextMenu2
{
    [PreserveSig]
    int HandleMenuMsg2(uint uMsg, uint wParam, uint lParam, IntPtr
plResult);
}

Can anybody suggest what I need to do to resolve this please?

The project was converted by VS2005 with no error messages but it is
obviously not happy with something!