The following message is more an FYI to those in the Internet community. I spent the last two days to restore functionality to my E.mail boxes in Thunderbird, following consistent and recurring crashes of Thunderbird, at the moment it began to PoP mail. Some elemental aspects to consider: Using Win XP/MCE/SP3. Using Avast as the AV package of choice, and up until July 8-10, I was using ZoneAlarm as the Firewall of choice. I am using Thunderbird ver. 18.104.22.168 (20080421). The problem began when something broke ZoneAlarm functionality. I have since come to find that this may have been a particular Windows update <KB951748> that caused the break. At that point, uninstalled ZoneAlarm, and installed COMODO Firewall Pro 22.214.171.1248. On top, decided to also go with COMODO' BOClean & SecureEmail as options. After installation, Thunderbird became unstable an non-functional; for every time Thunderbird attempted to initiate either PoP/IMAP, it would crash. I then proceeded to scour the net for known issues with COMODO products and Thunderbird. COMODO and THUNDERBIRD fora were not helpful. Subsequently, I initiated a process analysis. I will spare you from the details of the analysis. The SHORT story is that using a combination of SecureEmail and COMODO' Firewall Pro, proved to be troublesome on my machine. I proceeded to UNINSTALL COMODO Firewall Pro, BOClean and SecureEmail. Thunderbird still showed no prospect of functionality. I uninstalled and re-installed Thunderbird, which also proved to be a futile track. It turns out that SecureEmail had deep registry hooks, as did the COMODO' firewall, which did not go away with the uninstalls. Methodically, I rid the registry <kids, don't try this at home without adult supervision> from COMODO hooks, and reboot the system. This breathed life back into Thunderbird, again. I post this here with the hope that someone will be helped by my experience.