It all began in September at about the same time as AFG released their wonderful Pilatus PC-12. I succeeded in flying this aircraft without any mishap only once. Then things started to go wrong. It was at about the same time that I installed Microsofts SP2 upgrade and shortly afterwards Microsofts upgrade for FS9 arrived on the scene. I had also just upgraded the driver for my Nvidia Geforce4 card, so there where immediately many suspects. At first this was the only aircraft which seemed to cause the windows crash, and no matter what I tried it didn't solved the problem. And believe me, if you search the FS forums there are many suggestions.To cut a long story short and avoid painful memories of sleepless nights I'll jump to a point 3 weeks ago where I bought a new P4 with a 3.4Ghz porcessor and an ATI X600 graphics card and moved my Audigy2 sound card to it having disabled the onboard sound. Onto this I did a clean install of FS9 with Microsofts update to 9.1. But alas, believe it or not the PC-12 continued to cause XP to crash. I then started to reinstall many previously well flying aircraft. Some flew without triggering an XP crash, however, others did not. Five or 20 seconds into to a flight and the screen went black, and XP rebooted. This was driving me absolutely crazy. Using the default FS9.cfg and scenery.cfg didn't help. I fiddled with the grahic card settings and was an avid scanner of the forums to no avail.I should now mention that during all of this I had on may occassions run dxdiag which merely told me that everything was as in order. No problems encountered! Or so I thought. I did nevetheless begin to get the impression that the crash was more often caused by twin engined aircraft or more complex singles. But why? Then, last night I searched the forums once again for messages describing an XP crash similar to the one I've experienced. This time I succeeded in finding one, and only one, which seemed to have a common denomination and applied the solution. And guess what........... my XP crash has gone. And what fixed it? I reset the sound acceleration in the DirectX control box from FULL to BASIC. This did the trick!Suddenly everything became clear. I had updated DirectX to v9.0c at about the same time the AFG Pilatus was installed, And, of course it installed itself by default on the new machine so I gave it no or little consideration apart from again running dxdiag once or twice.So many thanks everyone for your contributions to the avsim forums and to one person in particular without whom myself and others would have been oblivious to the cause of this particular crash problem.Regards, Davidnr. Aarhus, Denmark

That's great it's solved, David. I make sure I make only onechange at a time & fly for a week to make sure no fault has beenintroduced. It cuts the variables.Intemittent faults are the worst. I had very occasional dead turn-offs of the PC needing cold rebooting. It turned out to be faulty power supply. It happened so rarely, I took it to be a faulty plug connection, or something.Peter Sydney Australia

I read about this a long time ago. I however have mine set to "standard" and that seems to work best for me.