OK. I found the problem but I'm not sure I can explain it technically. Well, I decided to start working on a different Windows 8 problem for a while. Specifically, my modem download speeds had become very inconsistent since migrating to Windows 8 and when I looked at my network adapter settings, I saw a bunch of new stuff supporting IPV6 and other Microsoft garbage that I couldn't even begin to figure out. Now, remembering back to my XP days, the only thing I really needed then was TCP/IP v4 so I deleted everything that Windows 8 would allow me to delete, and when I was done, the only choices left were TCP/IP v4 and v6, so I unticked the v6 and rebooted. So now I reran several browser speed tests and all was well again. FYI, what additionally prompted me to look into the network adapter settings was the fact that I saw I had an assigned TCP/IP v6 address (somewhere) in Windows 8 and my SB6120 modem was reporting a status of "offline" but it was still working (but not well). Anyway, I started to feel good about my success in resolving this problem so I went back to have a peek at the Thunderbird/Avast issue... and guess what, it was all fixed too! All notifications and reporting (as described previously in this thread) had returned to normal... just like they were in XP so I am one happy camper now! Many thanks to the two chaps that provided feedback and guidance. So, who would have technically figured out this solution? Certainly not me! Cheers.