I have 2 monitors. First plugged into nVidia graphics card and second one into the on-board graphics card. Main (1st) monitor is working perfectly fine, but the other one has random black spots like these:
They appear when I click on icons, or try to select something on the desktop. I've noticed that it usually happens when I work for a while on my main monitor without touching the second one. These spots usually disappear 2-5 minutes after I hit F5 on desktop. Any clues?