New
#11
Yes, I would recommend getting a 2TB or larger external drive (preferably Seagate) to use for Macrium images. I would also get it sooner rather than later.
The new local account shouldn't make any difference as to whether the update installs or not - it's just a safety net I wanted for future work on the system. Disabling the Avast shields *may* help, but I can't guarantee that's the only problem that exists.
I would really like you to try the Show/Hide Updates tool, to see if it will allow you to hide the update BEFORE you reboot, if you can. Tomorrow is ok - I know it's late for you.
I'm just concerned that the restore point(s) may eventually get corrupted, and you'll be stuck.
No problem at all. :)