Troubleshoot Internet Connection Problems at Microsoft.com

• http://windows.microsoft.com/en-us/windows-vista/Troubleshoot-Internet-connection-problems

You can also check the following:

• Your modem and/or router are both on and are not indicating errors. The problem may be with your Internet Service Provider (ISP). Contact your ISP for more information.

• If you are using a wireless connection, that you are using the correct access point.

• Your Domain Name System (DNS) server translates web addresses (URLs) into IP addresses and is usually provided by your ISP. If the DNS server is overloaded, you may be unable to view some or all websites. For example, if http://74.125.53.99 or http://74.125.159.105 work but http://www.google.com doesn't, you may have a DNS problem. You can use an alternative service such as OpenDNS ( http://www.opendns.com/ ) or Google Public DNS ( http://code.google.com/speed/public-dns/ ).

• Whether your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) is blocking connections to the Internet. For instructions on how to configure some programs, see this article -> Firewalls

Check and tell if its working.

It is possible that your anti-virus software is corrupting the downloaded files or otherwise interfering with downloading files by Firefox.

Try to disable the real-time (live) scanning of files in your anti-virus software temporarily to see if that makes downloading work.

See "Disable virus scanning in Firefox preferences - Windows"

• http://kb.mozillazine.org/Unable_to_save_or_download_files