Vanishing entities/walls/portions of dungeon?

withpuppies

So i've reinstalled recently, joining up with a group of friends from other games and did all my patching etc. Now for some reason, and this only happens in instanced dungeons, occasionally my character will flicker and vanish for a few moments, areas will flicker and vanish for a few moments or, fairly rarly, mobs will flicker and vanish for a few seconds. I've tried re-installing once already and know my computer can handle Neverwinter fairly easily, so i'm completely confused as to what's going wrong with my computer.