This issue is caused by a graphics-driver being below our minimum specification.
We therefore recommend that you update your graphics driver, to make sure it meets our standards. Once this is done, you should not encounter this issue anymore.
Since this is a computer related issue, we are not able to tell you how exactly to update your graphics-driver, but you can find this information online.
You can find the minimum computer specs for Star Stable Online on our website starstable.com under "Help" -> search for "Recommended computer specs"