Double Booting Issues

I am using MBP, 13inch, Late 2011, and running Mavericks. I have to install windows on it. So, I went via Boot Camp Asistant. Everything worked fine until system rebooted. At which point I got a blank screen with cursor in top left corner and nothing happened further. I forced shut down the machine and repeated 3-4 times only to get the same result. I was using Windows 7 Ultimate and I have verified that it is a 64-bit version. Please Help.