Every time you respawn, a random element of the HUD is disabled.
Malfunction is a skull in Halo: Combat Evolved Anniversary.
This skull can be found in the Scorpion section. After entering the Forerunner structure the Master Chief and any remaining Marines will encounter a huge gap with only one bridge. to the front right after entering, is a small pipe just below the current floor. On top of it lies the skull. This is just to the left of the turret sitting on the right hand side.
When players die, a random HUD item is disabled. This can be very lethal on Legendary if the player cannot see their health, shields or crosshair.