Before you call, check your computer’s case for a 25-character key. If you don’t have a sticker, make a note of when and where you bought the machine. Tell the folks on the other end of the phone that you had a genuine copy of Windows 7 or 8.1, but you used the Windows 10 Media Creation Tool to create a boot USB, then perform a clean install, before Microsoft posted details on the proper upgrade sequence. A good attitude and profuse thanks are called for. If they suggest you reinstall Win7 or 8.1 and upgrade again, tell them it would be a pain in the neck because you’ve been using the system for several days. Sometimes a gentle request for a supervisor works.
If you can’t get a key over the phone, you’ll have to reinstall Windows 7 or 8.1, and upgrade again. Sigh.
Who owns this PC?
When you set up Windows 10 Pro, you get to answer this question almost immediately: “Who owns this PC?”
Much mystery surrounds that dialog -- for example, if you own a small business, do you own the PC, or does your organization? -- and the details of the ramifications of the answers aren’t at all clear. To a first approximation, though, if you choose “I do,” you’re telling the installer that you want to provide either a Microsoft account or (with suitable gymnastics) a local account. If you choose “My organization,” Windows tries to join you to a domain or to Azure AD.
Even if you choose “I do,” you can still join a domain if you’re running Windows 10 Pro.
I’m told you should choose “My organization” if you use a business Office 365 account. Otherwise, the choice doesn’t make much difference. The real hairball appears if you set up the PC with your personal Microsoft account and later want to join a company domain with a company account. That leads to lots of jumping back and forth between personal and business accounts, apps, data, and restrictions. Windows 10 isn’t unique in this regard: The same mashup happens with Win7 and 8.1. There’s a brief discussion on the TechNet forum. Tim Anderson at The Register has a detailed discussion of the implications for using Office 365.
Trouble with video, sound, and other drivers
After basic installation problems -- typically ending in hangs or reboots -- the problem I hear about most involves lousy drivers. Sometimes the driver problem appears immediately after you install Windows 10. Sometimes, the problems don’t appear until you’ve rebooted the machine a few times and allowed Microsoft’s forced updates to wipe out your stable drivers.
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