We can't reproduce this problem so it might be due to a bug in your graphics card's driver software (we've seen a few problems caused by buggy NVIDIA cards). Try these steps:

  • Make sure you have the latest version of Golly (4.0).
  • Download and install the latest driver software for your card.
  • Open Settings > System > Display > Graphics settings > Graphics performance
    and set Golly to "High performance".