JMC47 - please let me know the specific situation that causes the crash so I can try to reproduce it here!
as for the sonud effects, I found sounddogs.com to be a really nice sight... there is a large selection, and you can purchase sounds (or specific portions of sounds) in any format/quality you want, with instant downloads... I used it for many of the sounds in the game. If I had a bigger budget, I would have used CD quality sounds instead of the 22010kHz versions I bought and of course I would have added more sounds in general... the game system allows for each prop to have its own "collision sound", but a lot of them are repeated right now...
p.s. once the linux version of Newton comes out, I'm hoping to compile a linux version as well, and if I can find an Ogre MAC user willing, a MAC version too!! I'm so happy I chose a multi-platform rendering engine