I tried a few more things including running in window mode, minimising memory use (by turning everything to low) and playing around with the "Graphics Rules.sgr" file. However all to no avail. There is a slim chance a future update of DirectX (there are a few minor patches I haven't installed yet), the ATI drivers or Sim City 4 may fix the problem but I'm not optimistic. Let me know if you have any luck. Cedars.