Since I last posted about this, I've removed Comodo, re-installed Sygate, removed Sygate, and put Comodo back on.
Why?
Just a few moments of madness... <img src="/ubbthreads/images/graemlins/biggrin.gif" alt="" /> My cursor happened to brush over the Comodo tray icon, and instead of the usual message ("... All systems are up and running.") it was displaying something about "initializing". And it went right on displaying that until I exited and re-started the program.
Rather than be sensible and do some research (apparently this is a known GUI glitch; the firewall was working fine), I uninstalled Comodo and put back Sygate. And then remembered my tiny concern about Sygate, which was that it appears to load very very slowly when I reboot... so slowly that everything else is up and running, and my email notification software has done its thing, before the tray icon show up. (For all I know, this could be just another GUI glitch...)
Anyway, I eventually went back to giving Comodo a try. Still may experiment with others. Or return to Sygate.