On a variety of computers, if I use your settings then the guides appear in the correct colour, not black.

It does appear to be video driver related, but I'm not sure if it might be impacted by another Windows display setting.

Closing PhpEd with documents open: when relaunching it, triggers the problem.
Closing PhpEd with no documents open: when relaunching it, triggers the problem at random.
It appears to be something being triggered on the initialization of the editor area.

Are you referring to flickering or guide colour?

I *always* close PhpED with documents open, but for me it works fine.

Once either problem is there, does it go away again? Most people seem to be describing an issue that is always there and never goes away.

I once wondered if ClearType might have something to do with the colour problem, but when I tested it, there was no impact.

I was talking about the guide colors:





On the first shot, I had no docs to be pre-opened. I closed PhpED and when reopening the docs got the problem.

I tried for some minutes (including a logout from windows and a restart) and only was able to see the guides "muted" two times within like a dozen tries.