I have a sample application that reproduces the problem.
When I start my application on a sandbox it always crashes or hangs.
You can try as follows:
1. Start the TestApp.app
2. Click to the "Open dir" and choose "cancel"
3. Click to the "Open file"
As result the application always crashes or hangs.
For non-sandboxed application nothing criminal as expected.

Sample of sandboxed application is available here.