I was playing on the level the library with bandanna and malfunction turned on when I saw a flood carrier form waddle behind a corner so I barraged it with grenades for about 30 seconds. It did not explode it simply flew up then fell repeatedly. I turned so I was facing the carrier then threw another 2 grenades. One detonated it and the next made the sound a plasma grenade does which was usual but then the infection forms became frozen in midair and did not respond to shots but green blood came out. The second plasma grenade refused to explode even when I shot and punched it. I switched to old graphics and there was no change. I then filmed the results. I walked to the next bit off the level when I heard a grenade explode and found the infection forms were gone. I will upload the video to YouTube howeverit only shows the result not the cause as I did not expect anything to happen