Black flickering during Game/Scene mode

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Hi, really sorry if this is posted somewhere else but I am struggling to find any answers.

I am very new to Unity and I am currently making my way through the Unity Essentials tutorials. During Game/Scene Mode I am seeing a lot of black flickering on the walls of the scene when I move the player/camera. Does anybody know what could be causing this?

Here is an example of what is happening:
unityexample

Many thanks.