Laminar Research is the makers of XPlane. Here's a quote from their forum:
Heh... OUCH. Seems that AMD's stuff doesn't work very well with the previous beta release and with the current one it just goes down in flames hard. Not good.'To those of you running v9 on ATI...we do not support v9 ATI. If you use v9 on your ATI hw and it catches on fire we will merely laugh derisively and say "We told you so".'