Set it to run on one core only. Either via the task manager (right-click on the respective process - you'll figure it out) or via my favorite (permanent) method:
imagecfg -a 0x1 "name_of_the.exe"
In the Command Prompt, of course.
I'm not sure which OS you're running and if the imagecfg program comes with it by default - I know it does with server editions, in resource kits etc. and I'm pretty sure it comes with Vista but I might have put it in my system32 folder a long time ago - if you don't have it, download it here:
http://www.robpol86.com/pages/imagecfg.php
P.S. There seem to be other solutions to the problem - type in "Beyond Good & Evil" "too fast" in Google to check them out if this one doesn't work.