My household recently acquired a much better computer than what was used previously. Allow me to list my specs, so you can share in my baffled-ness:
AMD Athlon 64 X2 Dual Core processor 4200+, at 2.22 ghz, 2 gig of RAM
Video card: nVidia Geforce 7900 GT
Now onto the problem. For installing FS2, what I did was I used the old 3.6.5 installer package to get everything needed for the actual program. Then, I upgraded the launcher, build, and VP files to 5.3 and 3.6.7, respectively. I have a couple other build exes, but... we'll get to that.
Okay, so I opened the launcher, selected the official 3.6.7 exe, fiddled with my options a bit, etc... and hit run. Game starts, start a new pilot, hit 'select,' main hall. Everything's dandy for about half a second. Then... either it locks up(not sure about it, since the music is still playing), or it's just taking a really long time to get to the next frame.
Sometimes it locks up, sometimes it'll get moving at the rate of about .1 frames per second.
Attempting with a more recent build won't start the game at all.