Black Screen & Freezing in game

[Verrin]

ISP: Optimum
Type of Internet Connection: Cable
Internet Connection Speed: 18Mbit/s
Date & Time: 5/13/2014 10:30PM EDT (most recent & worst occurrence)
Frequency: Sometimes
Character Name: Verrin Gunnar
Race: Elezen M
World: Gilgamesh
Class/Level: WAR 50
Area and Coordinates: The Lost City of Amdapor, aswell as other areas
Party or Solo: Party 4 & 8
NPC Name: None
Monster Name: Arioch for the worst occurrence

Past few days while fighting monsters sometimes every thing would freeze & then the screen would go black for about 3-10 seconds and then the picture would return with the game working.
It seems to happen when there's alot going on on the screen & the monster is using a big move.
Happened far more often then usual while tanking the lost city of amdapor
While fighting Arioch he did his animation when he becomes targetable and the glitch happened 3-4 times in a row & kept me from doing anything for about 30 seconds.
After turning down my graphics settings to the minimum it seemed to go away for the remainder of the dungeon.