When a Nether Reactor is manually deactivated (by removing the core before it appears "used up"), various issues occur:
Nighttime is eternal, unless one goes to sleep, but even then, daytime only lasts about 20 seconds, then quickly fades to nighttime.
Hostile mobs no longer spawn, though already spawned hostile mobs remain.
At times, hostile mobs behave oddly. e.g.: A spider might stay in water, ignoring the player, but will still cause damage if the player comes in contact with it.
Laws for gravity and liquids flowing are disabled..
Cleaning up old issues, please reply if affecting 0.9.3