All'attenzione degli utenti ZBrush che upgradano a Windows 10!
Seguire le istruzioni dell'annuncio di Pixologic per fare l'upgrade correttamente, altrimenti si rischia di disattivare la licenza e creare complicazioni inutili:

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Windows 10 and ZBrush
Posted by Matthew Yetter on 30 July 2015 10:11 AM

You are probably aware that Microsoft started rolling out Windows 10 yesterday as a free upgrade for all registered users of Windows 7 and 8. The tech blogs are all abuzz with excitement about how great the new OS supposedly is. Many of you are no doubt anxiously awaiting your turn to receive the update.
Please be aware that upgrading your operating system WILL affect your ZBrush activation. After the upgrade, ZBrush will think that it is on a new machine. In order to be proactive and help you avoid difficulties, we wanted to send you this information which will ensure that your upgrade is a smooth one. For your convenience, it is broken into sections based on individual user needs.

ZBrush Single-User and Volume Licenses (Anyone with a ZBrush serial number.)

BEFORE upgrading Windows, please launch ZBrush and use ZPlugin >> Deactivation >> Web Deactivation. It will shut that copy down and open your web browser to a page that asks for your registered email address. Submit that form and then be sure to also confirm on the page that follows. This will free your activation up so that you can activate again right away after upgrading Windows. You should not need to reinstall ZBrush after the upgrade unless you've also chosen to totally wipe your system before installing Windows 10. You will need to reactivate, however.
If you have already upgraded or if you forget to deactivate first then you will likely encounter a problem when you go to activate again after the upgrade. Upon filling in the Web Activation form you may receive a message that ZBrush has been activated too many times. In that case, click the button to View Activation History. This will take you to where you can request a repair to remove the lost activation from your serial number. We normally process these within 1-2 hours during normal business hours, after which you'll receive an email letting you know. At that point you can then activate successfully. Please note that normal business hours are M-F from 9 am to 5 pm, Pacific time.
Obviously, the best way to avoid issues is to deactivate ZBrush before you upgrade Windows!

ZBrush Floating Licenses (No Serial Number -- Managed By One of Your Servers)
If you're in a company or school environment that uses floating licenses, you have it easy. Just upgrade Windows and that's it! ZBrush needs no special preparation before upgrading the OS or after the upgrade is complete.

ZBrush Trial Users
You don't have to do anything with ZBrush before upgrading Windows. After upgrading Windows you will receive a message from ZBrush concerning a corrupt licenses. Don't panic! Just browse to your ZBrush 4R7 Trial folder and run the Pixologic Deactivation Manager found there. You will see a button to Reset. Click that, close the manager and restart ZBrush. It will now ask you to load your license file again and will then reactivate, continuing the Trial where you left off.

ZBrush to KeyShot Bridge
This uses the same activation system as for the ZBrush Trial. There's nothing you need to before upgrading to Windows 10. Just follow the instructions for Trial users, above.

Thank you for using ZBrush! We hope that your experience with Windows 10 is every bit as good as the tech gurus claim!