If you are running Windows (7, 8.1, or 10, mostly) and are using various Sophos, Avira, or Avast antivirus products, you may be experiencing slowdowns, freezes, or boot failures.
I'm running Windows 10 on this machine, with the Avast free home edition, and so far things are OK. (The machine updated and rebooted two days ago.)
I've had no issues either, running Windows 10 Pro with McAfee LiveSafe. There were multiple reboots before all the updates were applied, but it's working fine --- so far...
I had this issue on my work laptop...
Given some Windows updates can take 20-30 mins to complete it took a while to establish there was an actual problem!
As I'm a remote worker, I then had to go through the process of contacting the service desk (who were busy helping other people with the same issue), and authenticate accordingly. They then had to find my laptop in the asset management system in order to provide me the BitLocker key needed to boot into safe mode and remove the offending updates. It then took an age to reboot.
I pretty much lost an entire morning because of this, and I'm still waiting for the explanation as to why our patch testing procedures didn't pick this issue up?!