Avast 8 – Visit Community Forum – Firefox Loses All Add-Ons

After upgrading from avast 7 to 8 and attempting to go to the Community Forum on Firefox, 19.0.2 all add-ons are lost… But if Firefox is started previously, the add-ons are preserved.
(Sorry, version 8.0 .1483)

Did a clean install (i.e. uninstalled what I had, then downloaded and installed again) … problem went away