I am running multiple instances of Tomcat 5.0.28 on my localhost. I was able to expose these instances to my co-worker before(in the same network), so they can test my code. But all the sudden it's not working. The IE shows "Cannot find server or DNS Error". I ping my localhost from other host and it responses. I am able to see the instance on my localhost (http://localhost_name:port_numer/myApp) and don't see any error on the Tomcat logs. I wonder if it's some of my local setup causing this problem because my co-workers still can do it between them. Between last time I was able to do it and now, I installed Apache HTTP server, php, but not running any of them while I am having this problem. I am really running out of idea about this. Could any experts give any suggestions? I really appreciate it!