I’m sorry you’ve had such problems with the firewall.
Like Gordon points out, it’s not an entirely “install & forget” firewall. This has both positive & negative aspects (depending on your perspective).
On the positive, it provides a very high level of protection; as noted by the leaktest & termination tests. Also, the developers are very attentive to their users’ problems & requests, and work to resolve issues and provide new aspects to the program - all without crippling the security or bloating the program.
On the negative (here’s where the perspective thing comes into play), the user may need to do some configuring in order to get some specific functionality. This firewall, more than most others I’ve seen, requires some user interaction and understanding of what is going on. Thus, if you’re on a network where you are sharing access, files, printers, etc, things may be a little more complex. CFP is designed to work “out of the box” in the majority of situations; the use of wizards to create Zones and define those as Trusted Networks will normally resolve any issues with file/print/access sharing (provided that those shares are properly set up and working in Windows prior to CFP, and that the right executables are allowed access). Due to the way computers work, some users’ setups have proven to be problematic. However, once it is properly configured and working, there really isn’t much more to do except add applications and approve new components as needed.
On the negative (more perspective), because of the way CFP monitors changes to files, components, etc (in order to spot potential connectivity hijacks), there are sometimes conflicts with other applications that monitor the system, provide security, etc. This has been shown to result in some BSODs with certain conflicts; Comodo has worked very hard (with user feedback and help) to track those down and create updates that fix the conflicts. While this occurrence is unfortunate from a user perspective, it can happen with any software and computer; not just Comodo.
On the positive, Comodo provides free support http://support.comodo.com/, and these forums. Comodo has a strong staff presence in the forums, in addition to knowledgeable users and volunteer moderators; the majority of problems are able to be handled here efficiently. We all take pride in the products, and truly desire to help resolve any issues that arise.