This symptom may happen if you try to install Windows using a Windows 8 DVD. To install Windows 8 on a Mac that displays this behavior, create an ISO image of the install disc instead.

1. While started from OS X, insert the Windows 8 DVD in an external optical USB drive.
2. After the DVD mounts, Open Disk Utility from the Utilities folder (choose Go > Utilities from the Finder).
3. Select the USB optical drive so it is highlighted in the Disk Utility window.
4. Click on the New Image icon at the top of the Disk Utility window.
5. Select DVD/CD master from the Image Format pop-up menu, then choose none from the Encryption menu.

   
    

6. Give the new file a name, then click on Save. The Creating image dialog appears with a progress bar. It may take some time to create an image file from your Windows DVD.
7. Once imaging is complete, quit Disk Utility.
8. From the Finder, locate the disk image file you created earlier. Single click on it so its icon is highlighted, then press the Enter or Return key on your keyboard to rename the file. Change the disk image file extension from .cdr to .iso. When prompted, click "Use .iso" to verify this change.

   
    

9. Eject the Windows DVD.
10. Insert a blank USB 2 flash drive that is a least 16GB in size into a USB port on the computer. Boot Camp Assistant uses this drive to store the Windows 8 install media and support drivers during installation of Windows.
    Note: This flash drive needs to be formatted for the FAT32 file system and must use the Master Boot Record partitioning scheme. Use Disk Utility to check the format of the flash drive before proceeding, and erase or reformat the flash drive if necessary.
11. From the Go menu in the Finder select Utilities.
12. Open the Boot Camp Assistant app in the Utilities folder.
13. Click Continue.
14. Make sure the following options are selected (checked) in the Boot Camp Assistant window:
    √ Create a Windows 8 or later install disk
    √ Download the latest Windows support software from Apple
    √ Install Windows 8 or later version

    

15. Click Continue.
16. When prompted to select an ISO image, click Choose, then select the ISO image you created in Step 7, then click Open.
17. When prompted to save Windows drivers by the assistant, select the flash drive you inserted in Step 10 as your destination disk. Click Continue.
    A warning message appears. If you click Continue you will erase and reformat the flash drive. Click Continue to erase the flash drive.
18. A task status dialog appears with a progress bar. Do not disturb your computer during this process. Boot Camp Assistant creates Windows install media on the USB flash drive, and downloads and copies related Windows drivers to the same drive.
19. Next, a dialog appears asking for a password to install the Boot Camp Assistant helper tool. Type in your administrator password and click Add Helper.
20. Follow the on screen instructions to partition your drive and to install Windows 8.