uint ShowMessage(IntPtr hwnd,

    Function ShowMessage(ByVal hwnd As IntPtr, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpstrText As String, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpstrCaption As String, ByVal dwType As Integer, <MarshalAs(UnmanagedType.LPWStr)> ByVal lpstrHelpFile As String, ByVal dwHelpContext As Integer, ByRef lpResult As Integer) As Integer

The original definition on this page marshalled the strings as UnmanagedType.BStr which I think was incorrect since the underlying type is LPOLESTR. I experienced heap corruption and instability. ShowMessage also did not appear to be called reliably.

static extern TODO ShowMessage(TODO);

Declare Function ShowMessage Lib "iphlpapi.dll" (TODO) As TODO

    OLECMDID_SHOWMESSAGE         = 41,

    OLECMDID_SHOWMESSAGE = 41