issue example of Drupal 6 multilingual (i18n) written by Albert Skibinski from http://http://blog.merge.nl

this are some example issues you can face when implementing multi-language site in Drupal 6

Path prefix issues
For example, the language prefix in the url does not always work the way you expect. For example, let's say you have a site with two languages, Dutch and English (default Dutch), and would like a structure like this:

www.site.com/en/example-node
www.site.com/nl/voorbeeld-node

"example-node" is an English translation of the Dutch node "voorbeeld-node".

This tutorial is taken from http://drupal.org and originaly written by auris.
My suggestion is - implement the multi-language feature/function after clean install of Drupal 6. Then start with translation debugging and after this steps are donu put the site Live. Do not try to implement this to Live sites - you end up with lot of work and endless translation debugging.

Tutorial:

I just set up XAMPP on my Vista x64 PC and found that after installing Drupal 6 that the status report was throwing up an error.

HTTP request status
Your system or network configuration does not allow Drupal to access web pages, resulting in reduced functionality. This could be due to your webserver configuration or PHP settings, and should be resolved in order to download information about available updates, fetch aggregator feeds, sign in via OpenID, or use other network-dependent services.