wet ink marks INSIDE screen (virtual)

What the hell! Wet ink marks/stamps on the top right of the screen. 4 colours equi sized & spaced. Do nada until a non-max’d box/page is dragged ‘behind’ them.They get stained/smudged.

Maximising the page and the stains disappear but the screens virtual wet ink marks never move. These marks have duplicated twice so far. What the hell’s going on!?

Dell 5150, OS=XP, Spybot & AVG don’t see it