This article describes some possible reasons that neither Firefox nor other programs, like Internet Explorer, can load any web sites. Among the errors you can get if this happens:

• Server not found

For other situations where Firefox gives errors loading web sites, see Error loading web sites.

The fact that the problem isn't unique to Firefox suggests that you should look in places other than Firefox to solve the problem.

Table Of Contents

• Router
• Viewing system logs
• DNS
• DNS utilities
• ISP DNS
• Windows DNS caching
• Internet Service Provider
• Norton Internet Security
• Trend Micro Anti-Virus
• Spyware and other malware

Router

A recently installed router can cause problems. Contact your system administrator or refer to your router's documentation. If possible, see if you can connect without hooking up to the router.

Viewing system logs

System event logs may contain information on important events such as service failures and application updates and other activity.

1. To view the system event logs on Windows, in the Windows Taskbar select the START menu. Then, select Run.
2. In the textbox, enter eventvwr.
3. The Windows Event Viewer opens.

DNS

If your domain name system server (DNS server) becomes overloaded, you may be unable to view some or all web sites. Your DNS server translates web addresses (URLs) entered in your browser into IP addresses that are used on the Internet.

If you can open a web site by entering the IP address into the Location Bar but not the URL, you may have a DNS problem. For example, in the Firefox Location bar, enter http://64.233.167.147. If the Google.com web site is displayed, DNS may be the source of the problem.

DNS utilities

You can check the speed of your DNS server by downloading the "wdnslookup" utility for Windows, available here.

• Mac, Linux, and UNIX users can use the program "nslookup", which is part of the operating system.

Local DNS servers and your own computer cache the results, so a lookup may be much slower on the first attempt. For accurate results, you should use the "Clear Cache" button in the wdnslookup utility before resolving the host name you enter. This command clears the DNS cache in your computer yet leaves the server cache untouched.

ISP DNS

The DNS server is usually provided by your Internet service provider, so you should contact your ISP as a first step toward fixing the problem. This MozillaZine topic explains how to find a more reliable DNS server and also discusses an alternative service called TreeWalk.

Windows DNS caching

Windows 2000 and XP cache unsuccessful DNS lookup attempts, which means your failed attempts to contact a web site are stored. You may not be able to view a particular web site until the cached result expires.

• By default, the Windows DNS cache expiration time is 5 minutes.

As a workaround, you can flush the Windows DNS cache:

1. For Windows XP, in the Windows Taskbar select the START menu. Then, select Run.
2. In the textbox, enter ipconfig /flushdns. The DNS cache is flushed.
3. Try reloading the site.

You can permanently disable negative caching by editing the registry, as shown here. Registry editing is not recommended for novice users.

Internet Service Provider

If programs other than Firefox are also having problems connecting, the problem may be with your Internet Service Provider. Contact your ISP for more information.

Norton Internet Security

The popup blocker in the Addon Pack for Norton Internet Security can cause an interruption in the Symantec Network Proxy service, thereby interrupting your Internet connection. For more information, see the documentation that came with your software.

Trend Micro Anti-Virus

If you haven't updated your pattern file since April 2005 and suffer from 100% CPU utilization, see this article.

Spyware and other malware

It is possible that Spyware or other malicious software is causing connection problems. Use programs such as Ad-Aware or Spybot-S&D to scan your computer for malware.

Based on information from Error loading websites (mozillaZine KB)