There is no point in running the tests for more than a few hundred times. If you can do this with zero errors, it would appear to be a pass. In particular, flash tests should not be run for very long, as flash has a finite life.
Note that these tests will not spot all possible problems, only the ones they are designed to catch.
Your freeze is probably some memory problem, but could have other causes. It is not possible to diagnose these remotely.
