I'm experiencing a graphics issue that appears to be really spastic flashing triangular shapes that are often "originated" from certain shapes on-screen, such as a character's cloak, and stretched way across the screen, blinking and just being very annoying in general. This didn't always happen. I'm not very tech-savvy and I'm not sure what the issue is, though it sounds like a video card, I have no idea how to check for that. Any ideas?

Here are some specs:

Intel Core 2 Duo CPU E6850 @ 3.00 GHz (2 CPUs)
2048 MB RAM

Card:
NVIDIA GeForce 8600 GT
DAC Type: Integrated RAMDAC
Approx total mem: 1024 MB

Drivers:
Main: nv4_disp.dll
version: 6.14.0011.7519 (English)
Mini VDD: nv4_mini.sys
DDI Version: 9 (or higher)