I linked the above post to Broadbandreports topic for more exposure - See
http://www.dslreports.com/forum/r20276381-Update
I'm guessing changes were made in CC's as well as ZA's application - Possibly having to do with the CC updater piece being the trigger. I''m sure the CCleaner developers can elaborate, confirm or correct this.
Based on your AV detection results, I'd say you're surfing in some interesting territory and/or downloading some dodgy CODECs.