Recently characters both PC, NPC, and enemy alike have begun to appear and disappear randomly on my screen. They are there, just not showing, then if I move my character or change the camera angle, the character(s) in question will appear again. If I'm highlighting them, they don't disappear, but while unviewable I can not target them. This happens in all zones as far as I can tell.
Also, any characters with a fading effect (enemies disappearing after death, avatars, PCs after changing equipment, etc) appear on my screen with gaps of horizontal lines in them. I'm not sure if this is related or not.
I'm on Windows XP with an NVIDIA GeForce FX 5500 for video card. I've run virus/spyware/etc scans on my system as well as file checking POL and FFXI. I've got the most current version of DirectX and video drivers.
Thank you in advance for your time and help with this matter.