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#41
So your data resides on a different drive, okay.
Does this system have the HP Support software on it? If so, I would open it up, and make sure there are no updates for the software. Then I would run it to see if it pulls down any drivers for the system. You can also check online and compare your drivers in Device Manager to the latest on the HP website, to make sure you're up-to-date, especially with chipset and BIOS.
I believe this is the right page:
HP ProDesk 400 G1 Small Form Factor PC - Driver Downloads | HP® Customer Support
At this point I would write down your MBAM serial number and uninstall that as well. Disconnect your external drive. Then, right-click the ISO on the desktop, select MOUNT or open with File Explorer, double-click on setup.exe and try the upgrade again. Select YES to check for and download updates.
You can watch the video in this tut if you like:
Repair Install Windows 10 with an In-place Upgrade | Windows 10 Tutorials
Failing at this point, I think Navy's suggestion of a clean install would be the way to go.