Counter-strike 1.6 cannot be run, CSSource can be - Why?

Hello everybody,

Yesterday I installed Comodo Firewall 3.0 and spent some time with configuration. Everything seemed to be working well. But then when I tried to run Counter-strike 1.6 (from Steam engine) the game simply did not start (message box with “preparing to start Counter-Strike” appeared, disappeared and that was all). Interesting thing is that when I run Counter-Strike:Source, it starts without any problems and I can play.
I am 99% sure that this has something to do with Comodo Firewall as before I installed CF (instead of Kerio PF) I could play CS without any problem.

I allowed every actions for both steam and hl.exe. So as for firewall setting, configuration of CSS and CS should be the same. But CSS works while CS does not. And there is not any suspicious event in the firewall log.

Anybody has any idea what could cause this ??? Any hint is welcome.