Attached is my settings file. Place it in the Documents\Prepar3D v4 Files folder, start the sim and select the "Virtuali" profile in the Options->Graphics page.
However, I don't think it would change much to those affected, because I don't use any shader mods, I don't tweak my video card, and I don't have many add-ons, other than UT Live, some airplanes from PMDG, FS Labs, Leonardo and Aerosoft, and DD Chicago X city at KORD.
See this video here, for example:
This guy made a full flight from EGLL to KORD in the PMDG 747 and, arriving at KORD, he didn't had any flashing triangles so, it's *clearly* something affecting only some users with some kind of unusual combination of settings/tweaks/mods, since this guy surely have more installed add-ons then I have.