Quantum Fog can model physical situations that exhibit quantum mechanical behavior.
It is a tool for investigating and discussing quantum measurement problems graphically, in terms of network diagrams called quantum Bayesian nets. It simulates a general purpose quantum computer.
The following observation, by Alex (thanks Alex), may be pertinent to your problem:
"On my machine, QuantumFog 2 crashes when attempting to open a document on a locked volume (QFog2.dmg). The same document is opened without problems if it's on a writeable volume. Whether QuantumFog itself is on locked or on a writeable volume makes no difference." (Version 2.0)