Downgrading PHP to version 5.2
Why Downgrade?
Ubuntu 10.04 repositories, by default, have PHP version 5.3.
PHP 5.3 comes with a lot many improvements. But there are still many Drupal Third Party Modules which are yet to be ported to PHP 5.3, and so happens that Drupal 6 is not yet ready for PHP 5.3.
Till that is done (would take quite some time to happen), we would have to resort to downgrade to PHP 5.2.
How to Downgrade?