sorry… sometime it’s hard to read for me (english) and therefore I ask to be sure 
our experiance tell us, that also a “mini” mod can cause issues. May be you made a re-tests without any kind of installed mods ( you can simple re-name the existing comminity folder ). Then we can be sure that we not searching issues “at wrong side”.
If it also happens without mods, I fear it will hard to analyse ( we had already brainstorming about ). It may be then driver issue, or config thing because triple monitor setup, or the graphicscard, or… hmmm…