I set up Apache Web Server 2.0.55 and PHP 5.1.6 on my Windows XP 32-bit OS / 64-bit CPU. All was fine.
I installed Comodo Firewall and Comodo Anti-Virus.
Now, when navigating to http://localhost/ in IE6, it went nowhere. I could ping localhost and Telnet worked too.
I reluctantly uninstalled Comodo Firewall. No change.
Not suspecting Comodo Anti-Virus, I did a system restore and re-installed and set up Apache and PHP again. All was well again.
I installed Comodo Firewall again. All was still fine.
I re-installed Comodo Anti-Virus. Same problem!
I uninstalled Comodo Anti-Virus. All is well.