So what's up with my terrain?

I ditched my four year old machine, and spent the kids' inheritance on what was for me a powerful new beast, plus a new copy of Century of Flight. Goodbye to those nagging fs9 problems. Right? Wrong. Right from the start, this computer just doesn't like flying. Time and time again it'll start "loading terrain," and freeze at maybe 10% or 12%. Total block. I have to reboot. To complete a load of scenery is exceptional. And the old machine never did this to me! Any clues would be very welcome.athlon 4000+Geforce 6800GT2 gig RAM300 hard drive550 PSU