I have a Dell Optiplex 780 with two differents monitors connected to it .
This afternoon we had a power shortage , since that moment my Pc start and but no icons displays . Here is the message that i can see :
650702 [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR* pipe B underrun
650702 [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun


Please help !