Then I checked HTTP port (80) by
telnet in command prompt. It said
"could not open connection to the
host, on port 80: connection failed"
What is the telnet command you used? If you tried to access your computer on port 80, you need to have some software listening to accept the request, such as a web server. If you tried to access another site on port 80 and got that error, it's probably a problem with your network connection.
If you're referring to Kaspersky Internet Security, it may be the firewall. On the off chance that it is still running after you uninstalled it, it may have tried to reread the firewall configuration file, which may have been deleted, resulting in it blocking everything on that computer since it couldn't find any exceptions defined (just a possibility). You may want to try reinstalling the software, then disable and exit it all, and uninstall again.