When attempting to logon to Google Talk, the following message appears: ‘Could not authenticate to server’. This error also occurs when my friends attempt to use Google Talk.

This seems to be a problem some people have experienced when attempting to use Google Talk. Users have suggested a wide variety of reasons why this occurs, including: overloaded Google servers, or the problem being a bug in early versions of Google Talk. There seems to be little conclusive information available regarding this problem, so we will need to investigate this issue ourselves.

First, try downloading the latest version of Google Talk, in case this issue has been fixed in the latest release. You can download Google Talk from www.google.com/talk. Should the problem continue, you should check whether any firewall software on the computer is blocking Google Talk from accessing the internet. Open the firewall rules in your firewall application and check Google Talk has been granted permission to access the internet. You can find further information for configuring firewalls to grant Google Talk access to the internet at the following article from Google Talk support: www.google.com/support/talk/bin/answer.py?answer=24962.

Should your ISP require a proxy server to be configured to allow internet access, you may need to specify the proxy sever address in the Google Talk settings. Many ISPs operate transparent proxies, where all traffic goes through the proxy server even without the user manually configuring the proxy server address on their computer. That said, some ISPs still require the user to manually specify the proxy server. If this is the case for your ISP, open Google Talk and then click ‘Settings’. In the next window, select ‘Connection’ then enable ‘Use the following proxy server’ and enter the address of the proxy server. You do not need to worry about the proxy authentication settings, unless your ISP or network administrator requires you to enter a username and password to access the proxy - it is very unlikely you would have an authenticating proxy (such setups are generally only found in corporate environments).

Should all else fail, and you are still unable to use Google Talk, you may wish to try another VoIP client. Another very well-known VoIP application is Skype (www.skype.com). This application is free, has a very wide user base and is easy to use.