My desk top computer has a black screen when starting up

[haroldajones]

A few days ago my home built windows 7 computer did an automatic download. After the download installed itself I tried to turn on my computer. I got a black screen on my monitor. Was this download a virus?

 

[tech_twist]

possible not a genuine copy of windows if the background turns to black. check under system if it asking for a product key or serial.