I do recall there was an imac with a heat issue. If you give us some time (not today) I might be able to find more info about it. It caused it to be unpredictable. And if a system is unpredictable then LW is sure to bring out the worst in it, due to OSX's poor implemenation of Java. In fact, I think there may even be a thread about it on the forums. There's a 3rd party utility you can get to check for this problem. This problem had similar symptoms as you seem to have. As I recall I think it was one of the earlier G5 models unless I'm mistaken. As suggested, the symptoms didn't only necessarily happen with LW but was a problem non users of LW had. It's just that LW tends to bring these problems out to the surface more easily.