I’m trying to install Office 365 with a product key.
It seems to go fine, but then I get this message: Setup.X86.en-US_…exe Failed - Network Error.
All previous Office versions have been completely removed from this computer.
Does anyone have any suggestions?
Thanks.
Are you trying to install it on a machine that is offline? It sounds like the product installer is trying to connect to a server either to authenticate or to download components, but is failing
No, I was online.
But here’s something strange: when I tried to install it today
at Setup Office or Microsoft 365, it says it has already been installed.
Where on my computer will I find this program?
It’s not under “all apps.”
Thanks.
You could try running the uninstall tool, rebooting, and then reinstalling.
This sometimes helps (but sometimes it’s just a huge pain).
Thanks, Number. I did that once, but I’ll do it again. 
I would uninstall it, reboot, and install Open Office which is a free replacement for Microsoft Office:
http://www.openoffice.org/
Open Office is open-source and works on Windows, Mac and Linux, and it is always free including free updates.
LibreOffice is another alternative; works fine.
Sorry to have to ask what is potentially an insulting question… was your key legitimately purchased?
Yes, Mangetout, I paid good money for it! I didn’t want to take any chances
on it not working.