My MacBook Pro (15-inch, Late 2011), since start 3 days ago i keep trying to install Windows7 with original apps Boot Camp Assistant on El Capitan, it start without any problem. Once the installtion after create partition and restart to start install Windows7 from booting my DVD Drive. I using original Windows7's DVD, but is just can't start load windows's file and start install. It just left and blank black screen and a underscore on the left on my screen. I keep trying and trying many ways to install dual boot on my Macbook Pro, i try many solution before like those using USB Bootable, third-party apps like VmWare Fusion, all i get is fail result. 2 Months ago i still can get boot into Windows7, after that i didn't turn on my machine for 1weeks, it just show me a underscore on my left screen. Can any one help and tell me is that my hardware failure or my software problem. I really need Dual boot on this machine for some work.
Your Windows 7 DVD probably is defective. Either that, or the optical (DVD) drive is defective. I assume you are using your internal optical drive. If not then, then the external optical drive is defective or may not be compatible.
I assume you your firmware is up to date. Although, on a 2011 model, this should not be the cause of your problem.
Try this. Insert the DVD in the optical (DVD) drive. Restart the Mac and hold down the option key. A DVD icon should appear with the label "Windows". Select this icon and continue booting. If everything is OK, then the Windows installer should start. (If prompted, you may have to hit the space bar on the keyboard.) I assume the installer will not start, thus indicating either the DVD or the optical drive is at fault. If the installer starts, then exit and post a comment below.