One thing that I really need to stress here:
A significant percentage of the support tickets we've been dealing with over the last several days would have been avoided if the artist had simply read the documentation.
For example, we get a lot of support tickets (and forum posts) from people who complain that they upgraded and now when they go to download again they're getting a "page invalid" message. Yet the text immediately below that link explains the reason!
That email also states that after upgrading you need to create a Support account, or update your existing account. We need this info to help you efficiently. Yet most people haven't done it.
We have even had more than a few cases where someone clicked the upgrade link, clicked past the page where you can edit your information, clicked past the verification page where you make sure everything is right -- and then wonder why the system has their email address wrong and they can't activate.
In the download itself, right next to the ZBrush 3.5R2 folder there's also a PDF named "READ ME FIRST". It tells how to install, how to fix the most common error messages, and again stresses the need to register your Support account. Yet we still get many, many tickets from people who have done none of those things.
My point in bringing this up is that a lot of the issues that people are encountering are preventable. We have put considerable thought into every line of text that we provide during the upgrade and installation process, trying to be as proactive as possible. Unfortunately, that all goes to waste if nobody reads it.
Please help us help you! :)