Lines changing color on MT4

[Sputnik81]

Hello 

I thought that my monitor was dying but I've removed that variable.

Horizontal lines appear to be different colors on my screen depending on where they are drawn. This happens if I move their location by scrolling / zooming or if I highlight and move them. This is quite irritating as I use different colors in my trading system to indicate level importance. 

Has anyone else experienced this and does anyone have any suggestions?

This only started happening recently. I've been using MT4 for years without this problem. 

To clarify they're not changing from say red to blue but a bright green becomes a very dark green, a light blue becomes a dark blue. 

Thank you!

J