LOL....no probs, the clock is just one of things that will give the game away!
As for the black 'bouncing' well I dunno about that. It's more likely that the ceiling isn't being illuminated because the 'black' does not reflect any light. Before you go changing materials try the top of the units with the same material as the ceiling........use 'Region Render' to just re-render that part of the scene....it'll be a lot quicker.
If you find the same thing happens then you can rule out the material, and maybe look into what's lighting that part of the scene.
Anyway, enough rambling.
Regards.