You don't have to uninstall/reinstall HyperV
I ran into this same issue using the new Visual Studio 2015 Android emulator and Windows Phone emulator, while also trying to run VirtualBox clients. Unfortunately you can't run VBox at the same time as the other emulators; you just have to setup a new boot option and reboot to switch back and forth.
Open an administrative command prompt and run:
C:\>bcdedit /copy {current} /d "Windows w/ HyperV"
C:\>bcdedit /set hypervisorlaunchtype off
This will copy your current boot settings to a new boot option called "Windows w/ HyperV" and then will disable HyperV under your current boot option. You can run "bcdedit" with no parameters to check that {current} has the hypvervisorlaunchtype set to "off" and that the new section has hypvervisorlaunchtype set to "auto"
See Scott Hanselman's article for more information.
i7
does not mean that virtualization is supported or enabled. If it is, check your bios settings.