Sometimes if i dont have my cache set to call all (nParticles) maya will crash, but most times it just wont render anything (including an alpha).
I have made it work though and the results are great, with render times very very fast (as opposed to using mental ray for rendering this type of particle which is prohibitly slow!)
Has anyone out there in this fine community ever come accross this problem and maybe know a setting Ineed to have??? or a little trick under their sleeve??? otherwise i'll have to use the hardware render buffer (gasp!) which for some awesome reason doesn't render the color accumlation.