Hello guys.And Mr.Dan Prunier,thank you very much for your reply. >>1st thing, you need to sign your full real name according to these forum rules, thanks.I'm sorry about it.This is my first joining these forums. So I didn't notice the rules.I will sign my full name when I join these forums from now on. Thank you. >>Let us know how it goes. I tried according to your advice,installing C++ 2005 & 2008 (32 & 64bit),Net Framework4,deleting the FS9 cfg file,my MD-11 & FS9 froze again. So I cheaked error massage by Windows event logs, it was under FS9 application.Not a hardware issue nor my systems.I'm going to search another solution the freeze problem.Thank you very much for your advice.Hitoshi Kai