Joomla! 1.0.15 Stable
PHP 4.4.9 - I was using the old CB without any issues
Browser - i use the latest version of firefox
database version - 4.1.20-max-log
Community Builder 1.2.1 Stable
Both your Joomla and PHP versions are entirely obsolete, and both should be updated to current stable versions as soon as possible for security reasons.
CB 1.2.1 download has in bold red that it requires at least PHP 5 (preferably 5.2.6 to 5.2.9). Most hosting plans include an easy switch to PHP 5 in their CPanel. There are several threads here or on Joomla forums regarding upgrading Joomla from 1.0 to 1.5.