Steps:
1. Open the "repo" scene in Repo project (the scene has Nav Mesh baked with some Nav Mesh Agents)
2. Play the scene. After a few seconds, Editor stops responding with no error and no crash report.
3. If it doesn't freeze, stop and play again, wait for a few seconds.

Expected result:
Editor is still responding.

Actual result:
Editor is not reponding and not closing. It just freezed.

Notes:
1. If I disable Colliders on NavMeshAgent objects, no freeze.
2. Tried with a new scene, and baked a new Nav Mesh. It will also freeze, but not always. Like 20% (Open "newbake" scene to investigate).
3. Also tested repo scene in Windows Player, also freeze.
4. Tested DX11 and GLCore on Windows Editor, both freeze.

Reproducible with : 2017.1.0b1 (a29fc4a7eb25), 2017.1.0a6
Not reproducible with : 5.6.0p1