There is a record of a similar issue going back to the Windows 7 days. Read through the situation in the technical discussion in the following link: see if it describes your issue exactly --
Don't attempt the fix they suggest without making a backup first - it's tricky business.
The issue involves user profiles. There really shouldn't be a C:\Users\Temp\Desktop ... unless a users profile has such a problem that the default profile is used temporarily. I've heard (unconfirmed as yet .. I'm still checking) ... that it can happen if a user logs into a fresh Win10 upgrade without using an existing account from the previous Windows installation.
Just to make sure all your files from the Windows 8 installation saved OK: have a look in your Windows.old folder on your local hard drive (usually given drive-letter C).
The Windows.old folder allows you to have the option to return your computer to the previous version of Windows, if you do so within 30 days of your Windows 10 upgrade.
It is a simple matter to go back, if you are within that 30 day period:
Windows Start icon > Settings > Update & Security > Recovery > Go back to Windows 8
Let us know if you have questions.
[P.S. .... if you choose to go back to Win8, you still can try upgrading to Windows 10 again later ... as long as you do so by July 29, 2016]