My solution was simple. I had the same problem with the ground request in Level D 767 and FS2Crew voice for Level D, it crashed my FSX every time. What I did was the following steps:
1- Uninstall fsx_sp2_ENU
2- Reinstall fsx_sp2_ENU
3- Uninstall FS2Crew for Level D voice
4- Reinstall FS2Crew for Level D voice, Run as administrator.
That's it, my FSX is working fine. I hope this can work for every one.