Can't see art board - Whole thing is grey

[defaultf9toqtxexsa1]

This is my students Photoshop, we are remote learning and I need to exaplain how to fix this, but I have no idea. The layers will highlight when you move over them and the document is visable in the history and chanels but I can't remove this grey overlay to see the art board. Any ideas?

[defaultf9toqtxexsa1 · Accepted solution]

Resolved, there wasn't enough RAM, when she closed other programs Photoshop came back to life, 

[jane-e]

Thank you for letting us know — I've marked your answer "Correct" so it will help others.

~ Jane