Not upgrading? ok.. then it looked like that u are installing CB in an already existing joomla installation, not in a fresh one.

Some DB tables appeared to have existed, and not deleted during previous uninstallation. Try the tools found in CB > tools tab.

If you are not trying to upgrade, consider starting from a fresh Joomla installation, with a new DB / DB table prefix.

since that u are using 1.2 now, u might want to start a new thread in the 1.2 forum area:) .