Teleporters?

This is probably old, but what causes a player to seem to play normally on his screen but to others, he is teleporting around back and forth, almost as if he is invisible? Also, the player teleporting does not appear on the Player List, even if its 8v8.

Also, sometimes the player is on the List and can be kicked, but any player who joins in the player spot he was in also appears to be teleporting.

And yeah the one where anyone he kills suicides.