I have installed the above and everything seems to work fine for twenty minutes to half an hour and then FS9 just stops instantly. Program closes in an instant. No,message boxes about informing Microsoft or anything. I've been using FS since FS3 and have never known it stop, just like that. The PC is 3.2Ghz with 1Gig ram and 256Mb radeon X300 on-board video.I can't get to the bottom of it. Everything was fine before installation and the PMDG 737 NG 600/700 is fine, as are all other aircraft. Anyone out there with any ideas please?

That sounds heat related to me - is your case well ventilated? Try opening up the side of the case and see if the problem still occurs...

Geoffrey, Did you by chance install the FSInn 1.1 beta? I installed that and some really weird things started happening to my machine. My TCP/IP stacks would crash, requiring me to restart my network daemon, a simple disconnect from FSInn to restart it would crash the sim every time. On approaches with random planes, I would crash to desktop... no message, nothing. If you didn't, then I dunno, but I've had 5 people that I fly with in my VA say they've had similar issues as mine. In the end, I had to do a complete OS re-install ( uninstall didn't work for FSInn apparently ) and install FS9 from scratch. ... fun fun.

I must admit, I wondered that. Usually, the fans come on when the graphics card has a heavy 3d workload and I didn't notice that happening. However, I've just upgraded to a new pc with 2gb ram and 3.4 processor, which I'm about to set up. I'll install one thing at a time and keep testing. Thanks for your thoughts.

I haven't installed FSInn at all. Somemone reckons it could be a heat problem. However, I've just bought a new pc, so it's time to start over. thanks for your thoughts. All the best.