Can't boot into windows

I created a partition and installed windows. I then added it to parallels so that I could hop in real quick if I needed to. It has worked great for about a week and now whenever I try to boot into Windows 8 my screen flashes and then it stays black and I have to turn it off and back on. However I am able to launch windows 8 in parallels. Please help there are some programs that I need that just can't seem to run in parallels.