In XP and Vista64 I had been experiencing simulator problems. After about 10 simulations, the simulator would get into some sort of trouble. "unexpected simulator guest exit" was a common error. Crashes were more likely if I was or had been using the ProntoScript Console.

I don't yet have extensive experience with the v2.4.23.0 simulator, but it seems to be more robust in this respect.

My impression is that the v2.4.23.0 simulator loads faster, but there is some sort of background startup process that runs for a while.