Painter hard-crashing PC when working on 4k after update.

[defaultbc6srbi0ubuk]

I've been loving the new version's performance so far but often when I set a texture set's resolution to 4k it hard crashes my PC. No response, mouse freezes and leaving it to resolve itself (for an hour) doesn't solve anything. Also sometimes my project will look like this (image below), although a simple change that forces a recalculation will fix it. As the title suggests i never had this issue before the update. 
Any help would be very apreciated.

[Jeremie Noguer]

Could you try attaching a log file please (you can export it through the Help menu).

It looks like the kind of artefacts we would see on an unsupported GPU.