We've found a problem that repeatably crashes Particle Illusion. This has been tried this on different 3 Intel Macs. When in Emitter Properties, if you set the frame rate (in the bottom right of the window) to "0", then PI crashes. It just quits.
Also after the quit, when you reopen PI, the last file that was worked on, does not necessarily appear in the "Open Recent" in the FILE menu, even if it was saved before the crash.