This is a video tutorial on how to fix a problem that effects macs using bootcamp and windows 7 in which you see a black screen with a blinking white cursor when trying to load windows 7
Download this software EASYBCD
http://www.neosmart.net/EasyBCD/
Then follow the instructions shown in the video.
After that restart your computer and you should no longer have any issues.
WARNING: Don't change any other options in EasyBCD.
If used incorrectly you can make your current OS installation not bootable