Well, make that five. I spent three hours untangling the mess ZAAV's browser security (toolbar) evidently created in my Fx 3.63. Several add-ons got corrupted including Compact Menu 2 and adblock plus. I did a restore of a Fx profile backup with no benefit. I ended up uninstalling ZAAV, doing a system restore to before it's original installation, re-installed ZA and had the same problem.
So, uninstalled, system restore, and reinstall ZAAV without browser security and no problems with Fx.
This is an initial install of ZA on a month old Core i5 computer with Win7 64bit, updates current.. I was running Avast and used their removal tool, ccleaner and double reboot before installing ZA.