Some things that need clarification:

 

Is this happening every where? Is it seasonal (texture related)?

 

The next time it right after it happens go to the Win control panel and get into the administrator utilities. Drill down to the event manager and see what critical events occurred. They are ordered by most recent event first. That might point to the missing file when you click on the event to get more details.

 

It is known that the 9.1 patch fixes some seasonal CTDs by area that were present in 9.0.

 

There are also some useful troubleshooting utilities here:

http://technet.microsoft.com/en-us/sysinternals or sysinternals.com

 

http://technet.microsoft.com/en-us/sysinternals/bb545046 for disk utilities get filemon.exe. Start it up before you start flying. It keeps a log of your disk accesses and can get quite big so make sure you have plenty of empty hd space. After the CTD got to the filemon window and then save the log and shut it down.

 

It also might help to check your fs9 registry path using this free registry checker/repair utility from flight1:

 

http://www.flight1.com/view.asp?page=library

 

Regarding Speed 217's comment: He is I believe referring to the "fair use" provision of copyright law which for your own use allows you to make copies. In the lawyerese of the agreement of FS you'll find when you did the install one of the terms stating is that the software not be reverse engineered or modified nor basically defeat its copy protection. You have purchased a license to use the software under those terms and do not own it. Anyway all I am saying is you do not know the state of the NO CD patched file.

 

If you decide to try the 9.1 patch you most likely will need to have FS disk 4 in your install CD drive. When you install the 9.1 patch is will create a folder called backup under your FS9 folder that will hold the replaced 9.0 files that you can copy back. If that fs9\backup folder already exists by name, the 9.1 patch will not install. fs9.exe is one of the files replaced and stored with the 9.1 service pack.

 

I check out the error message when FS9 crashed and mfc70.dll may be the culprit.

mfc.dll is a library of "Microsoft Foundation Classes" used by many of the MS programming language applications that use directly or indirectly these objects. It could mean that something called the library routine that had an error that created the crash.

How can I fix this?