Yep, I too have been messing around with spotlight, and although it can be a very good tool I have had the same thing, crashing pretty much every time.
I got it to work for a while once, and even managed to texture a whole character, but 95% of the time it's shutting Z down completely. One out of 10 to 15 times really isn't a good sign, and although my setup isn't amazing, it should run it okay really.
I've been looking around for other peoples experiences, and from what I've seen, and from my own trial and errors, it seems texture size can play a big part of the problem.
Using a large texture just doesn't want to work. Keeping the size under say 1024x1024 can work for a while, but if you also have many pictures saved to use in one single spotlight file, that too can be trouble.
One guy tried it on 3 systems, and the third one (having quite similar specs to yours if I remember rightly) got it to work almost all the time.
All in all the potential for the tool is so great I hope they manage to sort the bugs out for the next update as I'd love to spend more time texturing using it.