Avast have been pushing out a major update in the last couple of weeks - it usually anoounces that its done it with a banner screen on reboot
I've noticed though that on some older machines with limited resources the banner screen faiils to load and stops windows booting
If that happens, its a trip to safe mode and use Autoruns to disable unwanted crud.
As to ZoneAlarm, it really offers little extra to anyone with a fully patched windows system with the windows firewall enabled