Unresponsive enemies

In some of the Halo games, glitches or AI faults can cause some enemies to be unresponsive.

Assault on the Control Room
In Assault on the Control Room, play through the level until you reach the part where you see Elites taking off in Banshees. Use a Sniper Rifle to snipe them; if you fail to kill any of them, revert to a checkpoint and keep trying. Once you've killed an Elite, take his Banshee and fly down to get a Ghost. Getting the Banshee isn't required, but by using one, you can avoid triggering enemies to spawn on top of the pyramid structure, allowing you to get there faster.

Drive the Ghost all the way up to the top, where you can open the door, but don't open it yet, or you will have done all of this for nothing. Instead, drive your Ghost up to the white triangle, and hover there so that you are directly above it. Make sure that the door is directly to your right.

Now begin strafing to the right and press up against the door. At this point, you sohuld be able to see a Grunt or two on the other side. If you can see your Ghost at least partially on the other side, you are doing it correctly. Once you are completely against the door, exit the Ghost. If done correctly, you should exit on the other side of the door.

There, you will see all of the Elites and Grunts, but they won't attack you. Because you never entered through the door, you never "activated" their AI, so they won't do anything. To "reactivate" them, just re-enter your Ghost, pull away from the door, and activate the control panel.

If the glitch doesn't work the first time, don't give up, and try at different angles.

Halo 2
In Halo 2, there seem to be many unresponsive enemies; however, they are not unresponsive in the usual sense. Instead, they are only unresponsive to you if their backs are turned -- they don't seem unresponsive as much as they do deaf. Here are a few examples.
 * The Sniper Jackal facing away from you after you come out of the tunnels in Metropolis.
 * The Heretic Elite on at the start of the level The Arbiter (Level), after he finishes patrolling. (Rarer than the Jackal.)