> > A long shot is the theme. Are you using some non-standard theme on your > > desktop? > > What is a theme? It's how the desktop looks - colours, icons, widgets that sort of thing. Complex themes have a "theme engine" underneath that does a lot of the hard work of drawing things on the screen > > > Finally, do you have a spare graphics card you could try in the > > machine? (This is just to make sure there's no hardware problem.) > > Only as a last resort. > Having already lost a couple graphics cards (not in this machine), > I open the case rarely and with fear and trepidation. > > When I hover over text, the black tape effect goes away. > Do graphics cards know about text or hovering? > Not really. But hardware issues may affect the rendering of some things. P.