I've tried re-installing FS9 and I also had the same problems when I tried older NVIDIA drivers and even when I disabled my PCIe card and used my onboard graphics. But I will take a look at that web site you gave me. Thanks.

*Finally*, I think I have found the cause of my problems. I ended up re-installing WindowsXP and FS9, and while I was setting up my system I realised that just before my problems began I had upgraded my motherboards onboard graphics driver - just to see what difference it made to the on board graphics, then I switched back to using my PCIe card again. I think that (somehow) the new Intel driver was causing graphics problems even though I was using my PCIe card (also the info with the updated drover did say not to install the driver if using 3rd party graphics hardware!).Anyway I have not had any of the types of crashes I mentioned in my original post. Of course I haven't proved that the Intel driver was the cause but right now It's working... and that's good enough for me!I'm still interested in any comments people have on this issue.