Build error

Hi guys,

I’m giving a presentation and every time I try to build the lights, it gives me this error and stops calculating. What can it be?

Output Log:

MapCheck: New page: Level_01 - Dec 9, 2016, 10:00:02 AM
MapCheck:Error: Error WorldSettings Maps need lighting rebuilt 
MapCheck: Info Map check complete: 1 Error(s), 0 Warning(s), took 56.618ms to complete.
LogEditorBuildUtils: Build time 0:04
LogD3D11RHI: Timed out while waiting for GPU to catch up. (0.5 s)
Job has failed! Job executable didn't exit cleanly. Exit code: -1066598273