I just finished upgrading to a new MacBook Pro running Mountain Lion. About after an hour or so of gameplay the game would random freeze, then immediately crash.
On my older MacBook Pro running Lion I had next to no issues running Torchlight 2. When upgrading to the new machine I used the Migration Assistant, so that could have caused an issue as well.
I've just turned on the "Log and report usage statistics", so hopefully that will help CodeWeaver track down what might be causing this issue.