When ups works in dc for a fraction and again work in ac power cpu remain on but

[mayuripatilcmpn]

when voltage low downs for a moment,ups works in dc power for amoment and then again works in ac power.But at this time I can't see my live screen,restarting computer using restart button doesn't work.But blue light on cpu remains as it is and blinking red light stops to blink.only option remains is power computer and again start it.what will be the problem? please help me

 

[popatim]

how about you list your system and UPS specs.
What all is connected to the UPS, how long these low voltage conditions last, and what these light you are talking about mean?