The Trend Micro Internet Security software package for Windows includes a firewall component, which controls the programs that can connect to the outside world and the types of connections that they can make. If Trend Micro Internet Security doesn't permit Firefox to connect to the Internet, Firefox may generate a "Server not found" error when you try to browse to websites.

1. At the top of the Firefox window, click the File menu, and select Exit.
2. Click the Windows Start button, then click All Programs > Trend Micro Internet Security > Trend Micro Internet Security to launch the Trend Micro Internet Security window.
   
   
   
3. Click the Home Network & Firewall Controls button on the left side of the Trend Micro Internet Security window.
4. Under the "Personal Firewall" heading, make sure the button at the top of the heading says ON If it doesn't, click it.
5. Under the "Personal Firewall" heading, click the "Settings..." button.
   
   
   
6. In the Personal Firewall Settings window, click the Advanced Settings button
7. In the Advanced Personal Firewall Settings window, click the Program Control tab
8. In the list of Programs, look for any mention of Firefox. Click its entry, then click Remove.
   
   
   
9. Click the OK button to exit the Advanced Personal Firewall Settings window.
10. Click the OK button to exit the Personal Firewall Settings window.
11. Click the X in the top-right corner of the window to close the Trend Micro Internet Security window.

Now open Firefox. If it doesn't connect, return to the Advanced Personal Firewall Settings window's Program Control tab as described above in steps 1 - 7. Then:

1. Click the Add to begin entering a new Firewall rule.
   • Next to Description, enter Firefox
   • Next to Target, Click the Browse.... Navigate to the Firefox program folder (Normally C:\Program Files\Mozilla Firefox\), then double-click the firefox.exe file.
   • Next to Settings, click the Simple radio button
   • Next to Firewall Response, click the Allow button.
     
     
     
2. Click the OK to save the rule and return to the Program Control tab.
3. Click the OK button to close the Advanced Personal Firewall Settings window.
4. Click the OK button to close the Personal Firewall Settings window.
5. Click the X in the top-right corner to close the Trend Micro Internet Security window.