High altitude

[slippalong]

Hi all.
      Have been using flight sim 2002 since it came out, no problems until recently.I have always flown ifr up to about 28000 feet.Have flown most of the planes around various places in the world but I have just started adjusting my flying altitude to flying up to 38000 for the big jets incliding a concord I downloaded,but as soon as I get to 30000 feet I cannot hold the nose down and they stall and crash I have tried adjusting fuel loads without any success so any help would be greatly appreciated
            Thanks

[elite marksman]

Make sure to adjust the trim properly. Dont go overspeed, in some addon aircraft going overspeed makes them behave erradically. Use the altitude hold and make sure you sustain speeds in excess of stall, to keep speeds up try slowing the acent to about 1000' per min or less above FL300.