I've had auto-update disabled because I do manual updates at my discretion. I don't think it's cool for applications to mess with the stability and integrity of my system at their whim. Anyway, somewhere in between running a manual update, renewing my registration, and running a full boot-time scan, Avast decided to allow itself to auto-update. That's kind of annoying.
What I find really irritating, is that when I came back to my computer after the boot-time scan, I find a Chrome window open (Chrome was not previously installed) to a page with Avast branding welcoming me to my "new browser". I wasn't asked to install this. There was also an auto-update window open completing an update, so I assume that Chrome was bundled in the update.
This is so unprofessional, Avast. This is the sort of stuff that drove me away from the other anti-virus software companies. I thought you were better than that.