#include <windows.h>
#include <stdlib.h>
#include <tchar.h>

typedef void(__stdcall * CallbackFunction)();

DWORD __stdcall ThreadFunc(CallbackFunction Callback) {

Callback();
return 0;
}


__declspec(dllexport) void __stdcall message(CallbackFunction Callback) {
    // Array to store thread handles
    HANDLE Array_Of_Thread_Handles[1];
    Array_Of_Thread_Handles[0] = CreateThread(NULL, 0, ThreadFunc, Callback, 0, NULL);
}

Private Sub Form_Load()
    Call message(AddressOf Callback)
End Sub

Public Declare Sub message Lib "MonitoringDirectoryDLL.dll" Alias "_message@4" (ByVal Callback As Long)

Public Sub Callback()
    On Error Resume Next
    Forms("MyForm").txtTest="test" 'this line executed well and the string "test" appears ok in the form.
    Forms("MyForm").Filter="" 'in this line Access crashes out
    Forms("MyForm").FilterOn=True
End Sub