New
#21
Nice find, good job! :)
If it was indeed Defender causing the problem, it's likely that the machine is infected.
Please downloadand install Malwarebytes Anti-malware(free version) from http://www.malwarebytes.org/products/malwarebytes_free/- UNtick 'Enable free trial of MBAM Premium' at the end of the installation- and update it, then run a fullscan in your main account, and Quickscans in any other user accounts.
Quarantineeverything it finds
Adding to what Noel recommended, also check root kit scanning.
I wouldn't know of this behavior, curious of the outcome now.