SVGA cable pins, maybe, or possibly the video/graphics card intermittent fault. Check the cable pins. Even try removing and reinserting the graphics card in its slot (either PCI or AGP). Monitors tend to go completely when faulty - not intermittently fade away. Have you a spare graphics card you can try? Belinea tend to be fairly reliable. I have a Belinea 15" TFT (Albeit with a dodgy red pixel) but the trusty old 17" Belinea is unused on the shelf - but it still works.