Originally this was "UI crash after unlocking computer", but that one seems to be fixed now (5.3.2). What remains however is that after unlocking, the UI/Canvas geometry is not rendered in the game view, until you forcibly cause something to change (e.g. resize the game view). Only happens on D3D9, suspect some canvas batch getting lost due to D3D9 device reset, and UI code does not detect that properly.

----- Original bug:
Steps to reproduce:

1. Open attached project
2. Open 'Main' scene
3. Lock PC by clicking Windows Key + L
4. Unlock it by entering the password
5. Observe the crash

Reproduced with: 5.2.3p2, 5.3.0f3, 5.4.0a5
Not reproducible with: 5.1.4f1