My acer notebook wont start up... Any help?

It had a virus and I installed webroot on it again to help take care of it. It was purchased a little more than a year ago, July of 2009. After the sweep, I quarantined whatever it found and shut the computer down. When I went to restart it it shows the "Acer, empowering people" thing like usual when you turn it on but then it just stops. The screen is still on, just black and it wont do anything else. Almost like it just freezes. Any help on how to fix this problem?