If you are getting a black screen when you start your Windows 7 PC then the following new Windows Help article may be of use. It discusses some of the possible causes and solutions to the problem.
“Video adapter problems are the most common cause of this issue. First, try to find out if there’s a problem with the cables you’re using or the way they’re connected. If you have an alternate way of connecting your monitor to your PC, try it. For example, if your monitor is connected using a HDMI connector, try disconnecting it and then connecting with a DVI or VGA connector instead.”