Artefacts for no reason?

[Ease]

I've recently installed a "new" game, Heroes of Might and Magic V:

Recommended Requirements :

- OS: Windows 2000/XP,
- CPU: Pentium 4 / Athlon 2,4 GHz or higher
- RAM: 1024MB or higher
- Video: 256 MB AGP 8x GeForceFX 6600 / RADEON x800 or higher video card
- CD/DVD-ROM speed: 32x
- Dolby Surround 5.1 sound processor

I have a Q6600 at 3.37GHz, 2GB of RAM, and a 512MB Radeon HD4850. I can play Crysis with all settings on High, on a relatively high resolution, with no problem at all. But this game; much simpler graphically, often produces artefacts on the screen. I often see a flush of small black squares roll across the screen. It's still playable, but irritating. FRAPS says its running at over 110 FPS, and my graphics card never breaches 60C. What could be causing this?

 

[[timko]]

Have you tried looking for the most recent update/patch for the game?

 

[Ease]

I have, but to little success so far. I found 1.6, which can only be used if you have 1.5. 1.5 requires 1.41, and 1.41 requires 1.4... which I can't find