I fixed:
MessageBox(hWnd, (LPCWSTR)pszOutBuffer, L"", NULL);
to:
int wchars_num = MultiByteToWideChar(CP_UTF8, 0, pszOutBuffer, -1, NULL, 0);
wchar_t* wstr = new wchar_t[wchars_num];
MultiByteToWideChar(CP_UTF8, 0, pszOutBuffer, -1, wstr, wchars_num);