There is nothing wrong with your monitor. This is not a test pattern.

Extreme magnification (2^609.8) of an area of the Mandelbrot set almost at the leftward tip of the x-axis. Created with Fractal Extreme.

Success! Uploading directly from blogger distorted the picture for some reason, perhaps because it was a .bmp instead of a .jpg. But saving the .bmp as a .jpg seems to have done the trick!