Q: windows cannot be instaled to this disk

Can you install the package?

Allow Gdisk to be installed using your Security preferences. You can try either W7 or W10.

If you are running El Capitan,

1. Boot into Local Recovery (Command+R) during power up.

2. Run Utilities -> Terminal.

3. Type csrutil disable and press return/enter.

4. Boot normally.

5. Type csrutil status in OSX Terminal and verify that is it disabled. If still enabled, repeat.

Once you have SIP disabled properly,

Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers. Please see the sample Q&A as an example. These steps can be repeated if you make a mistake before you get to Step 12, otherwise start from Step 1 for these steps. Step 6 has numbers which are typed with a space between the numbers. Please see the sample Q&A before you execute these steps.

Sudo gdisk /dev/rdisk0

P  (Print list of parts)

R  (Recover)

O (print current Hybrid MBR)

H (chooses Hybrid)

Partitions numbers to be hybridized: 2 3 4

Y  (Good for GRUB question)

N  (part 2 boot flag)

N  (part 3 boot flag)

Y  (part 4 boot flag make NTFS bootable partition)

O  (print current Hybrid MBR)

W (Write the new MBR)

Y (Yes! write the new MBR)

Reboot

Here is sample Q&A for this section. Please notice the Press Enter/Return.

Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y

Creating entry for GPT partition #2 (MBR partition #2)

Enter an MBR hex code (default AF): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #3 (MBR partition #3)

Enter an MBR hex code (default AB): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #4 (MBR partition #4)

Enter an MBR hex code (default 07): Press Enter/Return

Set the bootable flag? (Y/N): Y

Once the MBR is in place, retry your Windows installation.

You need to click on Format, as shown... (Reference - https://help.apple.com/bootcamp/assistant/6.0/#/bcmp09f5f773 ).

Are you able to install Windows after you follow these steps?

Is Windows fully installed and functional?

Please create back ups of OS X and Windows. Use separate external physical disks, if possible. Create a Windows System Restore point. Please review all Windows driver updates before you apply them.