Unresponsive to incoming network connections

I have two desktops running Windows XP and both started being totally unresponsive to the incoming network connections lately and I can't figure out what went wrong. I can't connect to any of the services that I was able to connect before (terminal server, cygwin sshd etc.), even though they are running and are accessible from with in the same computer. I can't ping by name (which used to work before) or even by IP address. I tried both from my other PC and laptop as well as from the router's ssh console itself (I use tomato firmware).

I updated both to sp3 and to the latest version of zonealarm and that is the only thing that I have done that is common to both, so I naturally suspected them at first. However, I can't point my finger at either. Here is how I diagnosed so far:
- Made sure windows firewall is not enabled (in fact the service is disabled and even trying to start the corresponding control panel app brings up the dialog that the service is not running and if I want to start it).
- In zonealarm, verified that my LAN is configured to be in trusted zone and that the security for trusted zone is switched off.

I also had a laptop not running zonealarm and updated to sp3 and that didn't have this problem, so suspecting that something is wrong with the latest version of zonealarm, I tried two experiments:
- Rebooted in safe mode with networking support, but no response to ping or telnet on a couple of known ports that I know are being listened. The telnet requests simply timeout.
- I then disabled zonealarm OSFirewall feature from the Program Control tab and then chose to not automatically startup with the computer. Rebooted and made sure the truevector service is not running and still there is no response for ping.

At this point, I am just assuming that this is not a problem with zonealarm itself, so looking for other directions. I am still trying to figure out if zonealarm is still playing a role even when its service is not started, so may be I should uninstall it and see if that makes any difference, however I would appreciate if anyone can provide me help on exploring other settings (outside zonealarm, unless any of you is familiar with zonealarm itself and suspecting it). Thanks a lot.

I just tried doing a clean uninstall of zonealarm and it still didn't help, so I installed it back. I followed this link to do a clean uninstall:

http://forums.zonealarm.org/zonela [...] e.id=49901

Any other ideas?