I had that for a while - certain guns had what looked like massive swords sticking out of them, and people would often have triangles going from their guns to either their target or a fixed location on the map.
Thought I needed a new card, but was advised on here to just re-seat my card, and they've since gone.
Haxor!!!
) and graphical anomalies (can't think of what it called but that will do) was due to my GPU overheating. try re-seating it as above, cleaning it, checking the temps etc