HELP HELP. confused, and lost on fsx now!

hi i posted earlier,

i am still having problems with my crashing after 20mins + / - or so... i installed fsx on my old machine and registered it, fsx did not run to my standard so i upgraded my pc with a new motherboard etc, kept my hard drive, reinstalled windows etc, reinstalled fsx and did as what it prompted on the screen! it kept crashing so i uninstalled it thinking it was a error in the installation... i then reinstalled fsx and the same thing happens! the pc was running hot so i have put a super cooler fan on the cpu, added 3 extra fans in the pc and the temp has dropped to normal working range!

what puzzels me is it worked ok on the old pc but the processer speed was slow heance the upgrade,

i have now got a ddr400 athlon 64 processor 3500+, 2 gig of ram with geforce 7600 graphics card.

after one occasion when i restarted the pc it came up with a error report with regaurds to drivers on the machine not working correctly?

i am positive everything on my machine is up to date, all the programs that are installed are not pirated or anything so i am stuck with why it does this?

could it be i activated the product code to many times or driver problem, a buged copy of fsx or a software error on windows xp home addition?

any addvice on this would be appreciated...