I just tested on the same config, except that I am on a 64 bit capable
MacBook pro. It compiles and run out of the box.
You could try to switch the active build configuration (generally
accessible in the Xcode toolbar). You could also try to change the
build settings for the F-Script target, using the build setting
inspector. In particular, try to modify the "Architecture" setting.
Other than that, I really don't know what is going on, and what to do
to fix it (well, maybe trying on 10.6)...
Philippe