Ok so it finally let me post. It seems like it is the screenshot I was trying to attach that it didn't like.
OK - the Painter problem: It freaks out on me sometimes while painting. It does irreversible damage to the work I've done and I have to start over each time this happens.
Part 2 - sometimes, a session goes well, and I save my work to continue it the next day, only to open the file the next morning and it looks glitched out in a similar way.
It's driving me a bit batty as I keep having to redo things.
PC - i7-6700 @ 3.4 GHz, 16GB RAM, GTX 1070
What can I do to stop this madness?