Installed Comodo Firewall version 3.0.13 on pristine (clean install) WinPro SP2 system with strictly conventional apps (office, iTunes, canon camera utilities). Problem: firewall crashes every time attempted to access a help file. Uninstalled Comodo and went back to Windows firewall.
On December 13, 2007, downloaded and installed Comodo Firewall version 3.0.14.276. Problems:
(1) Comodo will not allow access to a “trusted network” (the local LAN). Comodo saw the local network after install and asked if it should be trusted. Checked the block to allow full access to all other computers on the network, but NET VIEW shows that other PCs are not seen.
(2) Defense + will not allow a trusted application to write to disk. Re-applied the rule to trust syncappw.exe. Firewall says everything allowed by that app, but Defense+ still blocking it, even after multiple computer restarts.
(3) Defense+ blocks “trusted vendor” application. Same as (2) above.
(4) Comodo will not allow Comodo firewall to uninstall itself, even when exit Comodo. Comodo warnings keep blocking Comodo uninstaller. Apparently, Comodo doesn’t even trust itself.
These same problems occur on two different pristine Windows XP Pro computers (with only the most boring conventional programs installed; no file sharing, no games; no conflicting HIPS progams or spy washers).
Finally was able to uninstall Comodo, and went back to Windows firewall. 
Mac