I recently installed the Comodo Pro firewall, but I have had to uninstall it as it failed all 3 leak tests. In addition when it was installed I was unable to open IE Explorer and sometimes Firefox. I could only use the AOL interface (which uses IE Explorer) to access the internet.
Which 3 leak tests did it fail?
What version of the firewall did you use for the tests?
If you are referring to the CPIL suite of 3 leaktests, there are several things you should be aware of.
When you run each of the leaktests, you should get an alert about attempted outbound internet access. you should click BLOCK at this point. If you click ALLOW, the leaktest will succeed only because you have explicitly allowed the outbound access.
After running each leaktest, you must reboot. Leaktests may leave the network layer in an unstable state.