I am new to this forum, but I came here for a similar reason.
I use Firefox 3.5.3, and Gmail and Comodo. I think that I have both the firewall and Defense + running. I use both Gmail and Yahoo email. Only with Gmail, do I have a problem. I have not had any hanging problems, but when I compose a new email and try to send, the sending does not happen ! Also, when I want to change from the inbox to another window, it does not happen. I have waited 10+ minutes before I gave up with the "Still Working" icon flashing. I have used my Gmail account on a different computer and it functions normally using Win XP and a different firewall and virus software. I assumed that I might have some setting causing the problem. I have checked all of the settings in Firefox that I understand, but I do not understand many of the setting in Comodo.
The firewall security level is set to Custom Policy Mode. I do not know how to check the security level of Defense +.
Any thoughts are very welcome.