This is interesting & I think I understand why MSE is still on my desktop. I have both a custom built PC & an HP laptop. I worked getting Win10 installed on my custom built desktop 1st.
After hours of not being able to install I resorted to using the download tool to make a USB installer. After beginning the install I realized it was trying to do a clean install, not an upgrade. I canceled that & booted to the Win7 desktop & did an upgrade by picking the setup.exe from the USB drive while on the desktop. Yeah, I know it's confusing but I was able to upgrade so lets leave it at that instead of critiquing my install explanation.
Meanwhile, my laptop was offering the upgrade from the Windows Update window which never happened on my desktop. I used WU for the laptop upgrade & DON'T have MSE installed on it.
Not sure if that's the reason but it would seem likely. Just a thought.
If you successfully installed Win10 on the Desktop and it shows activated, then you could do a clean install using the USB.
If you're up for it
This time, a clean install, you DO want to boot the USB.
For a squeaky clean install - you can remove all information from the disk
Select custom install from the options given
When you're asked where you want to install, select Drive options (advanced) then select each partiiton and delete it. Do the same thing for all partitions until only allocated space is shown.
Make sure you have a good backup of your data before doing a clean install.
Also locate any license keys for software that your purchased, so you can re-install it.
I upgraded my Win7 box with USB media, then decided to test a clean install.
There are two times when you are asked for the key. The key is not needed after the upgrade was successful
The 1st time it asks, press skip this (lower left)
The 2nd time, press do this later (lower left)
Win10 completed the install and Windows is activated - I never entered a key.
I'm pretty sure this is by design and how it's supposed to work. The initial upgrade creates a key, encrypts it, and puts in firmware. Subsequent installs use the key from that location.
Thanks Slartybart. Your suggestion is a good one but I'm going to leave well enough alone. I have quite a number of programs & reinstalling them + digging up the software product keys would be quite the undertaking. MSE isn't worth that much of my time.
I only have one partition on C:. I don't think other drives will be affected. I guess I could unplug them before re-installing Win10.
I use Oops Backup software. Do I need anything else?
A bit confused by this thread. Assuming one has MSE installed will anyone upgrading to Win 10 from Win 7 carry over MSE and then have both MSE and Defender like the OP? If so, should MSE be uninstalled before upgrading?
I've always removed all 3rd-party antivirus on every system I've upgraded, just to avoid any problems, although MS have said that it would be done automatically during the upgrade.