With such a little information that you have put here, I find really hard to determine where the problem is. :)
Please, come back to the topic and post details regarding what has happened prior to the error that you get. What type of PC are you talking about – a desktop PC or a laptop? Are you able to
Please, provide more details regarding the situation and give information regarding the configuration that you have. If you have performed some troubleshooting steps already, please mention them too.